JP2573935B2 - Method for producing propylene block copolymer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION Technical Field The present invention relates to a method for producing a propylene block copolymer having high rigidity, high impact strength and excellent moldability.

2. Description of the Related Art Conventionally, in the presence of various types of stereospecific catalysts, propylene crystalline homopolymers or copolymers (hereinafter, both are sometimes simply referred to as polypropylene) are produced in the former stage, Producing a rubbery copolymer of propylene by copolymerizing propylene with another α-olefin in the presence of said polypropylene; and / or
It is also known to produce crystalline homopolymers or copolymers of other α-olefins, especially ethylene or ethylene-based crystalline homopolymers or copolymers. It is known that a composition having improved impact resistance at low temperatures while maintaining the excellent rigidity of polypropylene can be obtained by such a multi-stage polymerization method.

This composition is usually an intimate mixture of homopolymers or copolymers produced at each stage, but is generally referred to as a block copolymer. Such block copolymers are widely used, for example, for containers, automotive parts, low-temperature heat-sealable films, high-impact films, and the like.

As a catalyst for producing such a block copolymer, a titanium trichloride type catalyst has conventionally been used,
This requires a catalyst removal step, that is, a de-contact step, because the catalyst activity is low.

In recent years, a number of methods using a carrier-type catalyst have been proposed as methods for greatly improving the activity before the decontacting step becomes unnecessary (JP-A-52-98045, JP-A-53-88049, and JP-A-53-88049). 58-83016, etc.).

However, the carrier-type catalyst has a smaller molecular weight in the subsequent copolymerized portion than the conventional titanium trichloride-type catalyst, so the molecular weight distribution of the block copolymer is narrow, and the moldability during processing (spiral flow) is deteriorated. There was a problem of doing.

The present inventors have already found that by adding a special electron donor at the start of the first-stage polymerization as in the invention of Japanese Patent Application No. 60-59139, the moldability during processing can be greatly improved. Intensive investigations have been made to further improve.

On the other hand, for the purpose of improving the adhesion of the polymer particles, a method of adding an electron-donating compound at the start of the latter-stage polymerization has recently been proposed (JP-A-61-69821, JP-A-61-69822, and JP-A-61-6982).
No. 3 each publication).

However, these methods cannot improve the moldability of the block copolymer.

[Summary of the Invention]

The present invention aims to provide a solution to the above problems, and when performing a block copolymerization using a carrier-type catalyst, by adding a specific additive at the end of the pre-stage polymerization, the block copolymer It significantly improves the productivity.

That is, the method for producing a propylene block copolymer according to the present invention comprises a Ziegler formed from (A) a solid titanium catalyst component containing magnesium, titanium, halogen and an electron donor as essential components and (B) an organoaluminum compound. A crystalline propylene homopolymer or a propylene / ethylene copolymer having an ethylene content of 7% by weight or less is produced at 50 to 95% by weight of the total polymerization amount in the previous step in the presence of the Propylene and ethylene in the presence of a polymer or copolymer in a polymerization ratio (molar ratio) of 0/100 to 80/20 at a ratio of 5 to 50% by weight of the total polymerization amount
A method for producing a propylene block copolymer by polymerizing, characterized in that an alkoxytitanium compound and an organoaluminum compound are added during the subsequent polymerization.

Effect By producing a propylene block copolymer by the method of the present invention, it was possible to obtain a propylene block copolymer having high rigidity, high impact strength and excellent moldability using a carrier-type highly active catalyst. .

[Specific description of the invention]

Catalyst Component The catalyst used in the present invention is formed from component (A) and component (B), and falls within the category of Ziegler type catalyst.

Here, "formed from component (A) and component (B)" means that the third component which does not unduly impair the effects of the present invention or more preferably the third component which advantageously acts on the present invention. It should be understood that this does not exclude the case of including. A typical example of such a third component is an electron donor compound (component (C)) as a so-called external donor, and the catalyst formed from components (A), (B) and (C) is This constitutes a preferred embodiment of the present invention.

Then, it can be said that the catalyst of the present invention further contains a specific compound, that is, an alkoxytitanium compound and an organoaluminum compound in the latter stage of the block copolymerization.

Component (A) The solid titanium catalyst component (A) used in the present invention comprises:
It contains magnesium, titanium, halogen and an electron donor as essential components. Here, the term “indispensable component” means that, in addition to the case where the solid titanium catalyst component A consists of only these specific three components, at least the effect of the combination of these three components is maintained or this is unreasonably performed. Unless otherwise impaired, it means that additional components may be included. Such additional components are, for example, silicon halide compounds.

It is common to introduce magnesium into component (A) by magnesium halide, titanium by titanium compounds, and halogen by these compounds.

(1) Magnesium halide The magnesium halide is preferably a magnesium dihalide, and magnesium chloride, magnesium bromide and magnesium iodide can be used. More preferably, it is magnesium chloride, more preferably substantially anhydrous.

Magnesium halides include magnesium oxide, magnesium hydroxide, hydrotalcite, carboxylate of magnesium, alkoxymagnesium, allyloxymagnesium, alkoxymagnesium halide, allyloxymagnesium halide, organomagnesium compound, electron donor, halosilane , Alkoxysilane, silanol, A1 compound, titanium halide compound,
Magnesium halide obtained by treatment with titanium tetraalkoxide or the like may be used.

(2) Titanium compound Representative examples of the titanium compound include halogen compounds of trivalent and tetravalent titanium. Preferable halogen compounds of titanium are compounds represented by the general formula Ti (OR ¹ ) _n X _4-n (R ¹ is a C _{1 to} C ₁₀ hydrocarbon residue, X is a halogen), and n = 0, 1 or 2
Is a tetravalent titanium halide compound. In particular,
TiCl ₄ , Ti (OBu) Cl ₃ , Ti (OBu) ₂ Cl _{2 and the} like can be exemplified, and particularly preferred are titanium tetrahalides such as TiCl ₄ and Ti (OBu) Cl ₃ and monoalkoxytrihalogens. It is a titanium oxide compound. As the titanium compound, a titanium compound containing no halogen, specifically, Ti (OBu) ₄ or the like is also preferably used.

(3) Electron Donor Compound The electron donor compound, which is an essential component of the solid catalyst component (A) of the present invention, is at least one of specific compounds (a) to (c). Among these, the compound (c) is particularly preferred.

(A) one of the electron donor compounds is a polyvalent carboxylic acid,
An ester (a) of a polyfunctional compound selected from the group consisting of polyhydric alcohols and hydroxy-substituted carboxylic acids. Those suitable as esters of these polyfunctional compounds are, for example, those represented by the following formula.

Here, R ⁵ is a substituted or unsubstituted hydrocarbon group, R ² ,
R ³ and R ⁴ are hydrogen or a substituted or unsubstituted hydrocarbon group, and R ⁶ and R ⁷ are hydrogen or a substituted or unsubstituted hydrocarbon group, and preferably at least one of them is substituted or unsubstituted. A hydrocarbon group. R ³ and R ⁴
May be connected to each other. Here, as the substituted hydrocarbon group, those containing a hetero atom such as N, O, or S, for example, C—O—C, COOR, COOH, OH, SO ₃ H, —C—H—C—,
Those having a group such as NH _2.

Particularly preferred among these are diesters of dicarboxylic acids in which at least one of R ⁵ and R ² is an alkyl group having 2 or more carbon atoms.

Specific examples of preferred polycarboxylic acid esters include (a) diethyl succinate, dibutyl succinate, diethyl methyl succinate, diisobutyl α-methylglutarate, dibutyl methyl malonate, diethyl malonate, diethyl ethyl malonate, isopropyl Diethyl malonate, diethyl butylmalonate, diethyl phenylmalonate, diethyl diethylmalonate, diethyl allylmalonate, diethyldiisobutylmalonate, diethyldinormalbutylmalonate, dimethylmaleate, monooctyl maleate, dioctyl maleate, maleic acid Dibutyl, dibutyl butyl maleate, diethyl butyl maleate, diisopropyl β-methylglutarate, diallyl ethyl succinate, di-2-ethylhexyl fumarate, diethyl itaconate Aliphatic polycarboxylic acid esters such as dibutyl itaconate, dioctyl citraconic acid and dimethyl citraconic acid, (ii) diethyl 1,2-cyclohexanecarboxylate, diisobutyl 1,2-cyclohexanecarboxylate, diethyl tetrahydrophthalate, diethyl nadicate Aliphatic polycarboxylates, such as
(C) Monoethyl phthalate, dimethyl phthalate, methylethyl phthalate, monoisobutyl phthalate, mononormal butyl phthalate, diethyl phthalate, ethyl isobutyl phthalate, ethyl normal butyl phthalate, di-n-propyl phthalate, phthalate Diisopropyl phthalate, di-n-butyl phthalate, di-isobutyl phthalate, di-n-heptyl phthalate, di-2-ethylhexyl phthalate, di-n-phthalate
-Aromatic polycarboxylic acid esters such as octyl, dineopentyl phthalate, didecyl phthalate, benzyl butyl phthalate, diphenyl phthalate, diethyl naphthalene dicarboxylate, dibutyl naphthalene dicarboxylate, triethyl trimellitate, dibutyl trimellitate,
(D) Heterocarbon polycarboxylic acid esters such as 3,4-furadicarboxylic acid.

Specific examples of preferable polyhydric hydroxy compound esters include 1,2-diacetoxybenzene and
1-methyl-2,3-diacetoxybenzene, 2,3-diacetoxynaphthalene, ethylene glycol dipivalate,
Butanediol pivalate and the like can be mentioned.

Examples of hydroxy-substituted carboxylic acid esters include:
Benzoyl ethyl salicylate, acetyl isobutyl salicylate, acetyl methyl salicylate and the like can be exemplified.

Other examples of the polycarboxylic acid ester that can be supported on the titanium catalyst component include diethyl adipate, diisobutyl adipate, diisopropyl sebacate, di-n-butyl sebacate, di-n-octyl sebacate, and sebacic acid. Esters of long-chain dicarboxylic acids such as di-2-ethylhexyl can be mentioned.

Among these polyfunctional esters, those having a skeleton of the above-mentioned general formula are preferred, and more preferably phthalic acid, maleic acid, substituted malonic acid, etc.
The above esters with alcohols, particularly preferred are diesters of phthalic acid and alcohols having 2 or more carbon atoms.

(B) Still another group of the electron donor component, which is an essential component of the solid catalyst component (A), includes R ⁸ COOR ⁹ (R ⁸ and R ^{9 each} have 1 to 1 carbon atoms).
About 15 hydrocarbyl groups, at least one of which is a branched (including alicyclic) or ring-containing monocyclic ester group. R ⁸ and / or R ⁹ include, for example, (CH ₃ ) ₂ CH-, C ₂ H ₅ CH (CH ₃ )-, (CH ₃ ) ₂ CHCH _2- , (CH ₃ ) ₃ C-, C ₂ H ₅ CH (CH ₃ ) CH ₂ −, And the like. If one of R ⁸ and R ⁹ is a branched group as described above, the other may be the above group or another group such as a linear or cyclic group.

Examples of such a monocarboxylic acid ester include various monoesters such as α-methylbutyric acid, β-methylbutyric acid, methacrylic acid and benzoylacetic acid, and various monocarboxylic acid esters of alcohol such as isopropanol, isobutyl alcohol and tert-butyl alcohol. Examples can be given.

(C) Organosilicon compound As the electron donor compound, an organosilicon compound represented by the general formula R ¹⁰ R ¹¹ Si (OR ¹² ) ₂ or R ¹⁰ Si (OR ¹² ) ₃ can be selected. In the formula, R ¹⁰ is a cyclic aliphatic hydrocarbon group, preferably having 3 to 20 carbon atoms, more preferably 5 to 1
2, a bicyclic hydrocarbon group. R ¹¹ has 1 to 20 carbon atoms,
Preferred are 1 to 12 cyclic or chain aliphatic hydrocarbon groups. R ¹² is a cyclic or chain aliphatic hydrocarbon group, preferably a chain aliphatic hydrocarbon group having 4 or less carbon atoms. Specific examples are shown below by structural formulas.

Further, an organosilicon compound represented by the following formula can also be selected.

(Where R ¹³ is a branched hydrocarbon residue, R ¹⁴ and R ¹⁵
Is a branched or linear hydrocarbon residue, respectively, and n is 2 ≦ n
≦ 3).

R ¹³ is preferably branched from a carbon atom adjacent to a silicon atom. In this case, the branching group is preferably an alkyl group, a cycloalkyl group, or an aryl group (for example, a phenyl group or a methyl-substituted phenyl group). More preferably, R ¹³ is a carbon atom adjacent to the silicon atom, that is, the carbon atom at the α-position is a secondary or tertiary carbon atom.
Is a carbon atom of the class.

In particular, from the carbon atom bonded to the silicon atom 3
Those having a structure in which a number of alkyl groups are present are preferred. R ¹³
Has a carbon number of usually 3 to 20, preferably 4 to 10.
R ¹⁴ is usually a branched or straight-chain aliphatic hydrocarbon group having 1 to 20, preferably 1 to 10 carbon atoms. R ¹⁵ is an aliphatic hydrocarbon group, preferably having 1 to 4 carbon atoms.
Is usually a chain aliphatic hydrocarbon group.

 Specific examples are shown below by structural formulas.

(CH ₃ ) ₃ C-Si (OCH ₃ ) ₃ (CH ₃ ) ₃ C-Si (OC ₂ H ₅ ) ₃ (C ₂ H ₅ ) ₃ C-Si (OC ₂ H ₅ ) ₃ When these electron donor components are contained in the solid catalyst component A, it is not always necessary to use them as starting materials, and a compound that can be converted to these components in the process of preparing the solid catalyst component is used at the stage of the preparation. These compounds may be converted.

(4) Preparation of Solid Catalyst Component A In preparing the solid catalyst component (A), it is desirable that the magnesium halide be preliminarily treated. This preliminary treatment can be performed by various conventionally known methods, and specifically, the following methods can be exemplified.

(A) Grinding a magnesium dihalide or a magnesium dihalide and a halogen compound or a halogenated hydrocarbon compound of titanium, silicon or aluminum. The pulverization can be performed using a hole mill or a rocking mill.

(B) A magnesium dihalide is dissolved using a hydrocarbon or a halogenated hydrocarbon as a solvent and an alcohol, a phosphoric acid ester or a titanium alkoxide as a dissolution promoter. Next, the dissolved magnesium dihalide is precipitated by adding a poor solvent, an inorganic halide, an electron donor such as an ester, or a polymer silicon compound such as methyl hydrogen polysiloxane to the solution.

(C) Contact reaction between magnesium mono- or dialcolate or magnesium carboxylate and a halogenating agent.

(D) Contact reaction between magnesium oxide and chlorine or AlCl ₃ .

(E) A contact reaction between MgX ₂ .nH ₂ O (X is a halogen) and a halogenating agent or TiCl ₄ .

(F) MgX ₂ · nROH (X is a halogen, R is an alkyl group)
And a halogenating agent or TiCl ₄ for contact reaction.

(G) A Grignard reagent, a MgR ₂ compound (R is an alkyl group), or a complex of a MgR ₂ compound and a trialkylaluminum compound is converted into a halogenating agent such as AlX ₃ , AlR _m X
Contact reaction with _3-m (X is halogen, R is alkyl group), SiCl ₄ or HSiCl ₃ .

(H) A Grignard reagent and silanol or a contact reaction of polysiloxane, H ₂ O or silanol, followed by a contact reaction with a halogenating agent or TiCl ₄ .

For details of such pretreatment of magnesium halide, see JP-B-46-611, JP-B-46-34092, and JP-B-51-351.
No. 4, No. 56-67311, No. 53-40632, No. 56-50888, No. 5
No. 7-48565, No. 52-36786, No. 58-449, JP-A-53-4568
No. 6, No. 50-126590, No. 54-31092, No. 55-135102,
No. 55-135103, No. 56-811, No. 56-11908, No. 57-1806
12, No. 58-5309, No. 58-5310, and No. 58-5311 can be referred to.

The contact between the pretreated magnesium chloride, the titanium halide and the electron donor compound may be carried out by forming a complex of the titanium halide and the electron donor compound and then contacting the complex with the magnesium chloride. The contact may be performed by bringing magnesium chloride into contact with a titanium halide and then with an electron donor compound, or by bringing the magnesium chloride into contact with the electron donor compound and then contacting with a titanium halide.

The contact method may be pulverization contact such as a ball mill or a vibration mill, or magnesium chloride or an electron donor-treated product of magnesium chloride may be added to the liquid phase of titanium halide.

Washing with an inert solvent may be performed after the three- or four-component contact or at an intermediate stage between each component contact.

The solid contact component A thus produced has a titanium halide content of 1 to 20% by weight, a magnesium halide content of 50 to 98% by weight, and a molar ratio of the electron donor compound to the titanium halide of 0.05 to 0.05%. It is about 2.0.

Component (B) The organoaluminum compound used as the component (B) in the present invention is a compound represented by the general formula A1R _n X _3-n (where R represents 1 to carbon atoms)
12 hydrocarbon residues, X is a halogen or alkoxy group,
n is preferably 0 <n ≦ 3).

Such an organoaluminum compound is specifically,
For example, triethyl aluminum, tri-n-propyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, tri-n-hexyl aluminum, triisohexyl aluminum, trioctyl aluminum, diethyl aluminum hydride, diisobutyl aluminum hydride, diethyl aluminum monochrome Ride, ethylaluminum sesquichloride, diethylaluminum monoethoxyside and the like. Of course, two or more of these organoaluminum compounds can be used in combination.

The ratio of the organoaluminum compound (B) and the solid catalyst component (A) used in the polymerization of the α-olefin can vary widely, but is generally 1 to 1000, preferably 1 to 1,000, per titanium atom contained in the solid catalyst component. Is 10 ~
An organoaluminum compound can be used at a ratio of 500 (molar ratio).

Component (C) In the block copolymer of the present invention, various electron donors can be used as needed. As the electron donor, ethers, amines, organic silicon compounds and the like are preferably used. Specific examples are shown below.

(A) Ether compound An example of the ether used in the present invention is a compound represented by the general formula An ether represented by In the formula, R ^{1 to} R ³ are a saturated or unsaturated hydrocarbon residue, and generally have 1 to 1 carbon atoms.
An alkyl or alkenyl group (including a substituted derivative substituted with a halogen or a phenyl group) having 10 carbon atoms, preferably having about 1 to 4 carbon atoms, or having 6 to 12 carbon atoms, preferably having 6 to 10 carbon atoms. A phenyl group (including a halogen, an alkyl group (especially a lower alkyl group) or a substituted derivative with a phenyl group); However, one or two of R ^{1 to} R ³ are a phenyl group (including a substituted derivative with a halogen or an alkyl group (especially a lower alkyl group)). R ⁴ is a hydrocarbon group. Specific examples of such ether compounds include α-cumyl methyl ether, α-cumyl ethyl ether, 1,1-diphenylethyl methyl ether, 1,1-diphenylethyl ethyl ether, and α-cumyl tertiary ether. Butyl ether, di-α-cumyl ether, 1,1-
Examples include ditolyl ethyl methyl ether, 1,1-ditolyl ethyl ethyl ether, bis (1,1-ditriethyl) ether, and 1-tolyl-1-methylethyl methyl ether.

In addition to the above, 1,4-dionaire, 1,8-cineole, m
-Ether compounds such as Zionel can also be used.

(B) Amine compound The amine compound used in the present invention is a sterically hindered amine such as 2,2,6,6-tetramethylpiperidine and 2,2,6,6-tetraethylpiperidine.

(C) Organosilicon compound Specific examples of the organosilicon compound used in the present invention are found in the above-mentioned examples of the organosilicon compound (c) used as the electron donor compound contained in the solid titanium catalyst component. However, among these, dialkoxy or trialkoxysilane is preferably used. A specific example is represented by the following structural formula.

(CH ₃ ) ₃ C-Si (OCH ₃ ) ₃ (CH ₃ ) ₃ C-Si (OC ₂ H ₅ ) ₃ (C ₂ H ₅ ) ₃ C-Si (OC ₂ H ₅ ) ₃ The molar ratio between (C) the electron donor and (B) the organoaluminum compound is usually 0.01 to 1.0, preferably 0.02 to 0.5.

Block copolymerization The polymerization step of the present invention carried out in the presence of the catalyst, the first-stage polymerization to produce a crystalline homopolymer or copolymer of propylene, the addition of an alkoxy titanium compound and an organoaluminum compound, and propylene and ethylene It consists of three steps: post-polymerization in which polymerization is performed at a polymerization ratio (molar ratio) of 0/100 to 80/20.

First-stage polymerization In the first-stage polymerization, a propylene / ethylene mixture is supplied from propylene alone to a polymerization system to which the catalysts (A), (B) and, if necessary, (C) are added, and a propylene homopolymer or an ethylene content of 7% by weight or less. , Preferably 1.0
% Or less of the propylene / ethylene copolymer in one or more stages in 50 to 95% by weight of the total polymerization amount, preferably 60 to 90% by weight.
This is a step of forming the film so as to have an amount corresponding to% by weight.

If the ethylene content in the propylene / ethylene copolymer further increases in the first-stage polymerization, the bulk density of the final copolymer decreases, and the amount of by-product of the low-crystalline polymer greatly increases. Further, even when the polymerization ratio is at the end of the above range, the same phenomenon occurs as in the case where the ethylene content in the propylene / ethylene copolymer is large. On the other hand, if the polymerization ratio exceeds the above range, the amount of by-products of the low crystalline polymer tends to decrease, but the impact strength, which is the purpose of block copolymerization, is undesirably reduced.

The polymerization temperature in the first-stage polymerization is 30 to 90 ° C., preferably 50 to 80 ° C.
Degrees Celsius. The polymerization pressure is about 1 to 30 kg / cm ² .

In the first-stage polymerization, it is preferable to use a molecular weight regulator so that the final polymer has an appropriate fluidity, and it is preferable to use hydrogen as the molecular weight regulator.

Addition of an alkoxytitanium compound and an organoaluminum compound A preferred alkoxytitanium compound to be added in the first-stage polymerization is tetraalkoxytitanium, that is, tetraalkyl titanate. As a specific example,
Alkyl groups having about 1 to about 10 carbon atoms, particularly about 2 to about 8, include tetraethyl titanate, tetra n-propyl titanate, tetra i-propyl titanate, tetra t-butyl titanate, tetra n-hexyl titanate, tetraoctyl titanate, and the like. Among them, alkyl titanates having 3 or more carbon atoms are preferable, and tetra n is particularly preferable.
-Butyl titanate is preferred.

The amount of the alkoxytitanium compound to be added is usually 1 to 200 mol, preferably 5 to 50 mol, per 1 mol of titanium in the catalyst (A) component.

As the organoaluminum compound to be added in the second-stage polymerization, the organoaluminum compounds exemplified for the catalyst component (B) are used, and particularly preferred are trialkylaluminums such as triethylaluminum, tri-n-propylaluminum and trii-butylaluminum. Used.

It is usually added at a molar ratio of 0.1 to 1.0 with respect to the organoaluminum compound and the alkoxytitanium compound to be added.

The alkoxytitanium compound and the organoaluminum compound may be separately added to the polymerization system, or they may be brought into contact in advance and then added.

When adding both separately, the order of addition may be either.

The addition time of these two may be in the middle of the pre-stage polymerization,
Alternatively, it may be in the middle of the post-stage polymerization. The preferred timing of addition is at the end of the first-stage polymerization or at the start of the second-stage polymerization.

Post-stage polymerization The post-stage polymerization is followed by propylene,
Further introduction of the ethylene mixture, the ethylene content 20 to 10
0% by weight, preferably 30 to 100% by weight, more preferably 75% by weight
This is a step of obtaining a propylene / ethylene copolymer of up to 95% by weight in one or more stages. In this step, it is desirable to form an amount corresponding to 5 to 50% by weight, preferably 10 to 40% by weight of the total amount of the polymer.

If the polymerization ratio of the second-stage polymerization and the composition of the propylene / ethylene mixture are less than the above ranges, the impact resistance (particularly, low-temperature impact resistance) is poor, and the effect of improving the spiral flow is small. On the other hand, when the ratio exceeds the above range, operational problems such as a large increase in the amount of by-products of the low crystalline polymer and a significant increase in the viscosity of the polymerization solvent occur.

In the latter polymerization, a small amount of another comonomer may be allowed to coexist. Examples of such comonomers include α-olefins such as 1-butene, 1-pentene, and 1-hexene.

The polymerization temperature of the second-stage polymerization is 30 to 90 ° C, preferably 50 to 80 ° C.
Degrees Celsius. The polymerization pressure is about 1 to 30 kg / cm ² .

At the time of shifting from the first-stage polymerization to the second-stage polymerization, it is preferable to purge the propylene gas or the propylene / ethylene mixed gas and the hydrogen gas derived from the first-stage polymerization and shift to the second-stage polymerization.

In the latter polymerization, the molecular weight regulator may or may not be used according to the purpose. That is, when it is desired to increase the impact resistance of the final polymer, this step is preferably performed in the substantial absence of a molecular weight modifier.

Polymerization method The method for producing the copolymer according to the present invention is a batch method, a continuous method,
It can be carried out by any of the semi-batch methods. At this time, a method in which polymerization is performed in an inert hydrocarbon solvent such as heptane, a method in which the monomer used is used as a medium, and a method in which polymerization is performed in a gaseous monomer without using a medium , And a method in which these are combined can be adopted. The first-stage polymerization and the second-stage polymerization may be performed in separate polymerization tanks.

Prior to subjecting the solid catalyst to polymerization, preliminary polymerization can be carried out under milder conditions than planned (see JP-A-55-71712 and JP-A-56-57814).

EXPERIMENTAL EXAMPLES The following examples are provided to further illustrate the present invention. These are illustrative of some of the embodiments of the present invention and are not intended to limit the present invention.

Example-1 (1) Preparation of solid catalyst component 75 ml of purified heptane and 75 ml were placed in a 500 ml glass three-necked flask (with a thermometer and a stirring bar) with a nitrogen replacement.
Of titanium tetrabutoxide and 10 g of anhydrous magnesium chloride. Thereafter, the temperature of the flask was raised to 90 ° C., and magnesium chloride was completely dissolved over 2 hours. The flask was then cooled to 40 ° C and magnesium chloride
A titanium tetrabutoxide complex was precipitated. This was washed with purified heptane to obtain an off-white fixation.

65 ml of a heptane slurry containing 20 g of the precipitated solid obtained above was introduced into a 300-ml glass three-necked flask (with a thermometer and a stirring bar) having a 300 ml internal volume purged with nitrogen. Next, 25 ml of a heptane solution containing 8.7 ml of silicon tetrachloride was added over 30 minutes at room temperature, and further reacted at 30 ° C. for 30 minutes. 90 ° C
For 1 hour, and after completion of the reaction, washed with purified heptane. Next, a heptane solution 5 containing 1.6 ml of phthaloyl chloride
The mixture was added to 0 ml and reacted at 50 ° C. for 2 hours, then washed with purified heptane, further added with 25 ml of titanium tetrachloride and reacted at 90 ° C. for 2 hours. This was washed with purified heptane to obtain a solid catalyst component. 3.22 titanium content in the solid catalyst component
% By weight.

(2) Polymerization n-heptane dehydrated and deoxygenated after sufficiently replacing a 200-liter stirred autoclave with propylene.
Introduce 60 liters and triethyl aluminum (B) 6.
0 g, 3.0 g of the solid composition (A) and 6.4 g of diphenyldimethoxysilane were introduced at 70 ° C. under a propylene atmosphere.

The first-stage polymerization was started by heating the autoclave to 75 ° C. and then introducing propylene at a speed of 9 kg / hour while maintaining the hydrogen concentration at 2.0%.

After 215 minutes, the introduction of propylene was stopped and the polymerization was continued for 75 minutes.
C. for 90 minutes. 0.2 kg / cm ^{2 of} propylene in the gas phase
Purge until G.

Next, 6.8 g of tetra-n-butyl titanate and 1.0 g of triethylaluminum were added, and after the autoclave was cooled to 60 ° C., the post-stage polymerization was fed at propylene of 1.57 kg / hour and ethylene at a feed rate of 2.35 kg / hour for 87 minutes. It was carried out by doing.

The slurry thus obtained is excessively dried and dried.
36.4 kg of a powdery block copolymer was obtained.

 Details of the results are as shown in Table 1.

The weight ratio of the polymer formed in the first-stage polymerization and the second-stage polymerization and the weight ratio of propylene and ethylene in the second-stage polymerization are calculated values on a feed basis.

(3) Measurement of physical properties (a) MFR MFR was measured according to ASTM-1238.

(B) Ethylene content The ethylene content in the product was calculated from the IR absorption spectrum.

(C) Measurement of practical physical properties The following additives were blended with the powdery polymer obtained in each of Examples and Comparative Examples, and pelletized by an extruder under the same conditions, and a 4 mm-thick sheet was prepared by an injection molding machine. Then, physical properties were evaluated.

Additives 2,6-di-tert-butylphenol 0.10% by weight RA1010 (manufactured by Ciba-Geigy) 0.05% by weight Calcium stearate 0.10% by weight PTBBA-AL (manufactured by Shell Chemical) 0.10% by weight Measurement of physical properties According to

(A) Flexural modulus: ASTM-D790 (b) Izod impact strength (0 ° C): ASTM-D-256
(With notch) (c) Spiral flow measurement method The spiral flow measurement method was performed using a SJ type (in-line screw type) injection molding machine in a mold having a cross section of 2 mm x 8 mm under the following conditions.

Molding temperature: 240 ° C Injection pressure: 800 kg / cm ² Injection time: 6 seconds Mold temperature: 40 ° C Injection rate: 50 g / second Comparative example-1 When performing block copolymerization, except that nothing is added at the end of the first-stage polymerization Example 1 was repeated under the same conditions.

 As a result, 33.4 kg of product powder was obtained.

 The details of the results are shown in Table 1.

Examples 2 to 4 Example 1 was repeated except that the weight ratio of the first-stage polymerization and the second-stage polymerization and the weight ratio of propylene and ethylene in the second-stage polymerization were changed in performing the block copolymerization.

 The results are shown in Table 1.

Example-5 The example was repeated except that the additive at the start of the first-stage polymerization was changed from diphenyldimethoxysilane to 4.2 g of tert-butylmethyldimethoxysilane when performing the block copolymerization.

 The results are shown in Table 1.

Example -6 (1) Preparation of solid catalyst component 75 ml of purified heptane and 75 ml of a three-neck glass-made three-necked flask (with a thermometer and a stirrer) having a 500 ml internal volume purged with nitrogen.
Of titanium tetrabutoxide and 10 g of anhydrous magnesium chloride. Thereafter, the temperature of the flask was raised to 90 ° C., and magnesium chloride was completely dissolved over 2 hours. The flask was then cooled to 40 ° C and magnesium chloride
A titanium tetrabutoxide complex was precipitated. This was washed with purified heptane to give an off-white solid.

65 ml of a heptane slurry containing 20 g of the precipitated solid obtained above was introduced into a 300-ml glass three-necked flask (with a thermometer and a stirring bar) having a 300 ml internal volume purged with nitrogen. Next, 25 ml of a heptane solution containing 8.7 ml of silicon tetrachloride was added over 30 minutes at room temperature, and further reacted at 30 ° C. for 30 minutes. 90 ° C
For 1 hour, and after completion of the reaction, washed with purified heptane. Next, a heptane solution 5 containing 1.6 ml of phthaloyl chloride
0 ml was added and reacted at 50 ° C. for 2 hours, then washed with purified heptane, 25 ml of titanium tetrachloride was further added and reacted at 90 ° C. for 2 hours. This was washed with purified heptane, and 1.0 g of tert-butylmethyldimethoxysilane was further added.
For 2 hours to obtain a solid catalyst component. The titanium content in the solid catalyst component was 2.56% by weight.

(2) polymerization n-heptane dehydrated and deoxygenated after sufficiently replacing a stirred autoclave having an internal volume of 200 liters with propylene.
Introduce 60 liters and triethyl aluminum (B) 6.
0 g and 3.0 g of the solid composition (A) were introduced at 70 ° C. under a propylene atmosphere.

The pre-stage polymerization was started by heating the autoclave to 75 ° C. and then introducing propylene at a rate of 9 kg / hour while maintaining the hydrogen concentration at 2.5%.

After 215 minutes, the introduction of propylene was stopped and the polymerization was continued for 75 minutes.
C. for 90 minutes. 0.2 kg / cm ^{2 of} propylene in the gas phase
Purge until G.

Next, 6.8 g of tetra-n-butyl titanate and 1.0 g of triethylaluminum were added, and the temperature of the autoclave was lowered to 60 ° C.
This was performed by feeding at a feed rate of 2.3 kg / hour for 87 minutes.

 The results are shown in Table 1.

Example 7 (1) Preparation of solid catalyst component A solid catalyst component was prepared in the same manner as in Example 7, except that 1.5 g of norbornylmethyldimethoxysilane was used instead of tert-butylmethyldimethoxysilane.

(2) Polymerization Example 7 was repeated.

 The results are shown in Table 1.

Example-8 (1) Preparation of solid catalyst component Example 7 except that 1.5 g of tert-butyltriethoxysilane was used instead of tert-butylmethyldimethoxysilane.
A solid catalyst component was prepared in the same manner as described above.

(2) Polymerization Example 7 was repeated. The results are shown in Table 1.

Comparative Example 2 Example 1 was repeated under the same conditions except that only 6.8 g of tetra-n-butyl titanate was added at the end of the first-stage polymerization when performing the block copolymerization.

 The results are shown in Table 1.

Comparative Example-3 Example 1 was repeated under the same conditions except that only 1.0 g of triethylaluminum was added at the end of the first-stage polymerization when performing the block copolymerization.

The results are shown in Table 1.

[Brief description of the drawings]

FIG. 1 is to assist in understanding the technical contents of the present invention relating to the Ziegler catalyst.

Claims (1)

(57) [Claims] 1. A propylene crystal in the preceding stage in the presence of a Ziegler-type catalyst formed from a solid titanium catalyst component comprising magnesium, titanium, halogen and an electron donor as essential components and (B) an organoaluminum compound. Propylene / ethylene copolymer having an ethylene content of 7% by weight or less is 50 to 95% by weight of the total polymerization amount.
In a later step, propylene and ethylene are mixed in the presence of the homopolymer or copolymer in a polymerization ratio (molar ratio) of 0/100 to 80/20 at a ratio of 5 to 50% by weight of the total polymerization amount.
A method for producing a propylene block copolymer, which comprises adding an alkoxytitanium compound and an organoaluminum compound during the second-stage polymerization in the method for producing a propylene block copolymer.