JPH07145220A - Production of propylene block copolymer - Google Patents

Abstract

PURPOSE:To obtain a propylene block copolymer excellent in the balance between rigidity and impact resisting strength, and molding workability while preserveing a catalyst activity and suppressing the formation of a solvent-soluble by-product. CONSTITUTION:This propylene block copolymer is produced by performing the following processes (1) and (2) in the presence of a catalyst composed of a titanium trichloride composition and an organoaluminium compound. The process (1): a propylene comopolymer or a propylene-ethylene copolymer containing ethylene of <=5wt.% is produced in an amount of 60-90wt.% based on the total polymer weight. The process (2): an ethylene homopolymer or an ethylene-propylene copolymer containing propylene of <=30wt.% is produced in an amount of 10-40wt.% based on the total polymer weight. At any point after the finish of the polymerization of the process (1), a specified amount of an ester compound is added to the product and at least a part of the process (2) is performed in the presence of the ester compound.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION

TECHNICAL FIELD The present invention relates to a propylene block copolymer having high rigidity, high impact strength and excellent moldability,
The present invention relates to a polymerization method which provides a highly active and low-crystalline component by-produced in a reduced amount.

[0002]

2. Description of the Related Art Generally, a propylene polymer produced by using a titanium trioxide composition as a catalyst has excellent processability, chemical resistance, electrical properties and mechanical properties. It is processed into molded products, films, sheets, fibers, etc. and used for various purposes.

Further, for the purpose of enhancing the impact resistance while maintaining the rigidity of the product, research on block copolymerization using a titanium trioxide composition as a catalyst has been actively conducted.

[0004]

However, in order to increase the mechanical strength (rigidity and impact resistance) of a product, generally, if the rigidity is increased, the impact resistance is lowered, and if the impact resistance is increased, the rigidity is lowered. In general, the moldability tends to decrease, and if the impact resistance is to be increased, the proportion of solvent-soluble by-products increases, which causes productivity deterioration such as deterioration of powder properties. There was a point.

These problems hinder the expansion of applications of propylene-based polymers, and there has been a demand for urgent improvement. [Outline of Invention]

[0006]

[Means for Solving the Problems]

<Summary> The present invention aims to solve the above problems, and aims to achieve this object by adding a specific additive to the latter stage of block copolymerization.

That is, the method for producing a propylene block copolymer according to the present invention comprises the steps (1) and (2) below in the presence of a titanium trichloride composition and an organoaluminum compound. A method for producing a combined product, wherein the amount ratio [ester compound / organoaluminum compound (molar ratio)] with the organoaluminum compound present in the polymerization system after the completion of the polymerization in the step (1) is 0.1 to 2 0.0 ester compound is added, and at least a part of the step (2) is carried out in the presence thereof. Step (1) Propylene homopolymer or propylene / ethylene copolymer having an ethylene content of 5% by weight or less is 60 to 90% by total weight.
Producing wt%. Step (2) Ethylene homopolymer or propylene content is 30% by weight
The following ethylene / propylene copolymer was used in a total polymerization amount of 10
~ 40 wt% producing step. <Effect> By producing a propylene block copolymer by the method of the present invention, rigidity is improved and impact strength is improved at the same time. Therefore, the balance between rigidity and impact strength is further improved and molding processability is improved. A propylene block copolymer can be obtained. Furthermore, according to the present invention, the production of solvent-soluble by-products can be suppressed while maintaining the catalytic activity. Although the reason for this is not clear, it is presumed that, by using the ester compound in a specific amount ratio in the polymerization step (2), the catalytic active sites act to increase the molecular weight of the produced polymer. . [Detailed Description of the Invention] <Catalyst component> In the method for producing a propylene block copolymer of the present invention, a catalyst comprising a titanium trichloride composition and an organoaluminum compound shown below is used. Here, "consisting of" means that the components are listed (ie, titanium trichloride composition and organoaluminum compound).
It is to be understood that this does not mean that it is only the case, but that it does not exclude the coexistence of other components within a range that does not impair the effects of the present invention. Titanium trichloride composition The titanium trichloride composition of the present invention is typically one in which titanium tetrachloride is reduced to titanium trichloride and then activated. The reduction of titanium tetrachloride can be carried out with an organoaluminum compound, metallic aluminum, a grineer compound, metallic titanium, hydrogen or the like, but the reduction with an organoaluminum compound is preferable from the viewpoint of the activation treatment to be carried out later.

Such a reduction product may be used as it is as the titanium trichloride composition in the present invention, but it is subjected to an activation treatment according to a conventional method for a transition metal component of a Ziegler type catalyst. Is preferably used as a catalyst component. In this case, the activation treatment includes pulverization treatment, complexation / extraction treatment and the like, but the complexation / extraction treatment is preferable from the viewpoint of catalytic activity and product properties.

The following describes the preferred method of making the titanium trichloride composition. Examples of the organic aluminum compound used for the reduction of titanium tetrachloride include methylaluminum dichloride, ethylaluminum dichloride, n
-Propyl aluminum dichloride, ethyl aluminum sesquichloride, dimethyl aluminum chloride, diethyl aluminum chloride, di-n-propyl aluminum chloride, trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, diethyl aluminum hydride, diethyl aluminum bromide and the like.

Of these, dialkylaluminum chloride is preferable, and specifically, diethylaluminum chloride and di-n-propylaluminum chloride are used.

The reduction reaction for obtaining a reduction product is -60 to 60
C., preferably in the temperature range of -30 to 30.degree.

The molar ratio of the organoaluminum compound to titanium tetrachloride can be freely changed according to the purpose. The preferable results are obtained in the case of diethylaluminum chloride per mol of titanium tetrachloride of 0.5 to 1.
5 mol, and in the case of ethylaluminum sesquichloride, it is 1.5 to 2.5 mol. The reduction reaction is preferably carried out in an inert hydrocarbon solvent such as pentane, hexane, heptane, octane and decane.

In a preferred embodiment of the present invention, the titanium trichloride composition obtained by such a reduction reaction is treated with ethers. Typical ethers are monoalkyl dialkyl ethers (each alkyl group preferably having about 1 to 10 carbon atoms), and specific examples thereof include diethyl ether, di-n-propyl ether and diether. -N-butyl ether, diisoamyl ether, dineopentyl ether, di-n-hexyl ether, di-n
-Octyl ether, di-2-ethyl-exyl ether, methyl-n-butyl ether, ethyl-isobutyl ether and the like. Among these, di-n-butyl ether and diisoamyl ether are preferably used.

The treatment of the titanium trichloride composition with ethers is advantageously carried out in the presence of a diluent. In that case, an inert hydrocarbon compound such as hexane, heptane, octane, decane, benzene, or toluene is preferably used as the diluent.

The amount of ether compound to be used is 0.05 to 3.0 mol, preferably 0.5 to 1.5 mol, per mol of titanium trichloride. The treatment temperature is preferably 0 to 100 ° C. The processing time is not particularly limited, but 20
It is usually performed in the range of minutes to 5 hours. The reaction product with the ethers is preferably washed with an inert hydrocarbon compound such as heptane and then subjected to the next electron acceptor treatment.

After the ether treatment, a treatment with an electron acceptor is carried out. Examples of the electron acceptor at that time include titanium tetrachloride, silicon tetrachloride, phosphorus pentachloride, vanadium tetrachloride, zirconium tetrachloride and the like. Of these, titanium tetrachloride is preferred.

The treatment with an electron acceptor is also preferably carried out in a solvent, in which case a preferred group of solvents is an aliphatic hydrocarbon, specifically n-heptane, n-
Octane, 1-octane and the like can be mentioned. Halides of aliphatic hydrocarbons are also useful, and specific examples thereof include carbon tetrachloride, dichloroethane, trichloroethylene, tetrachloroethylene and the like. Aromatic compounds are also suitable as the solvent, and specific examples thereof include toluene, xylene, chlorobenzene, orthodichlorobenzene and the like.

The treatment with the electron acceptor is carried out by dissolving the electron acceptor in a solution and dispersing the titanium trichloride composition obtained as described above, preferably treated with ether as described above. It is preferable. In that case, the concentration of the electron acceptor in the electron acceptor solution is usually preferably in the range of 10% by weight to 80% by weight.

The treatment temperature with the electron acceptor is from room temperature to 1
A temperature of 00 ° C, preferably 50 ° C to 80 ° C, is selected. The processing time is usually in the range of 30 minutes to 4 hours.

The titanium trichloride composition can be obtained by the above-mentioned production method. Such a titanium trichloride composition,
Although it can be used as it is as a catalyst for polymerization in combination with an organoaluminum compound (detailed later), the titanium trichloride composition particularly preferred in the present invention can be used for additional treatment such as treatment with alcohol or other electron donating compound. It was obtained by attaching.

As the alcohols to be treated with alcohols, monohydric alcohols or diols having 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms are preferable. Specifically, methanol, ethanol, n-butanol, tert-butanol, n-hexanol, n-
Monovalent or divalent aliphatic or aromatic alcohols or phenols such as octanol, 2-ethyl-hexanol, n-decanol, cyclohexanol, phenol, benzyl alcohol, ethylene glycol and propylene glycol can be mentioned. Among these, aliphatic monohydric alcohols such as ethanol and n-butanol are preferable.

Alcohol treatment of the treated product of the titanium trichloride composition obtained above is carried out by washing the treated product of the titanium trichloride composition with a hydrocarbon solvent, and then contacting it with alcohols. It can be carried out. When the one treated with this alcohol is used, the by-product ratio of the amorphous polymer (AP) becomes smaller, and the stereoregularity and bulk density of the produced polymer are improved.

The alcohol is used in an amount of 0.01 to 1.0 mol, preferably 0.02 to 0.2 mol, based on 1 mol of titanium trichloride. The treatment temperature is 0 to 100 ° C., preferably 0 to 30 ° C. The treatment time is not particularly limited, but a range of 5 minutes or more and 10 hours is preferable.

The hydrocarbon solvent used for washing the treated product of the titanium trichloride composition before the alcohol treatment is an inert hydrocarbon solvent such as pentane, hexane, heptane, octane, decane, cyclohexane,
And the like, and aromatic hydrocarbons such as benzene and toluene are preferable.

The titanium trichloride composition of the present invention has a milder condition than the planned polymerization conditions (main polymerization).
If necessary, it may be one that has been subjected to prepolymerization by contacting with an olefin in the presence of an organoaluminum compound.

The polymerization temperature of the prepolymerization is usually 40 to 90.
C., preferably 50 to 80.degree. The polymerization pressure is usually 1 to 50 kg / cm ² G. The olefin used in the prepolymerization is a monoolefin or diolefin having about 2 to 6 carbon atoms, and the organoaluminum compound that may be used may be selected from those described above as the one used in the main polymerization. Organoaluminum Compound The organoaluminum compound used in the present invention can be selected from those commonly used as an organoaluminum compound for a Ziegler type catalyst. One representative example of such a compound is alkyl aluminum chloride. Specifically, dimethyl aluminum chloride, diethyl aluminum chloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride, di-
Examples thereof include n-propyl chloride and di-i-butylaluminum chloride. The alkyl of the alkylaluminum is preferably one having 1 to 6 carbon atoms, particularly preferably 2 to 4, and the number thereof is preferably 2. Therefore, particularly preferred organoaluminium compounds in the present invention are diethyl aluminum chloride and di-n-propyl aluminum chloride.

The amount ratio of the organoaluminum compound to the titanium trichloride composition is 1 to 50, preferably 2 to 10 in terms of Al / Ti atomic ratio. Ester Compound The ester compound used in the present invention is an ester of an inorganic or organic acid having an action of increasing the molecular weight of the polymer produced in the polymerization step (2). When the acid is a polybasic acid, it is common that all of its acidic groups are esterified, and when the alcohol is a polyhydric alcohol, it is common that all of its hydroxyl groups are esterified. Is.

Preferred specific examples of such esters are:
Esters of silicon-containing acids, phosphorus-containing acids and carbon-containing acids, such as silicates, phosphates,
Examples thereof include phosphite ester and carboxylic acid ester.

When the ester is an ester of silicic acid, phosphoric acid and phosphorous acid, these acids are such that the silicon and phosphorus atoms have substituents, as long as they can be present as inorganic acids. May be. In that case, the substituent is typically an alkyl group having about 1 to 8 carbon atoms, a phenyl group or a tolyl group, or halogen. Further, when the ester is an ester of a carboxylic acid, the carboxylic acid is typically a mono- or dicarboxylic acid having about 1 to 10 carbon atoms (including carbon of a carboxyl group).

The hydrocarbon group of the alcohol when the ester is regarded as a dehydration condensation product of acid and alcohol is
An alkyl group having 1 to 8 carbon atoms, a phenyl group (that is, the "alcohol" in the present invention includes phenol) or a tolyl group is particularly preferable. And
The alcohol is preferably a monohydric alcohol.

Specific examples of such compounds are as follows. First, examples of the silicate ester include ethyl silicate, butyl silicate, diethyldiethoxysilane, phenyltriethoxysilane, and t-butylmethyldimethoxysilane.

Examples of the phosphoric acid ester include trimethyl phosphate, triethyl phosphate, tributyl phosphate and the like.

Examples of the phosphite ester include trimethyl phosphite, triethyl phosphite, tributyl phosphite, triphenyl phosphite and the like.

The carboxylic acid ester includes an aliphatic ester, an alicyclic ester and an aromatic ester.

Examples of the aliphatic ester include ethyl acetate, 2-ethylhexyl acetate, ethyl valerate, vinyl acetate,
Methyl methacrylate, butyl crotonate, etc. can be illustrated.

As the alicyclic ester, methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate,
Examples thereof include methyl cyclohexanecarboxylate and the like.

Examples of the aromatic ester include ethyl benzoate, n-butyl benzoate, 2-ethylhexyl benzoate, phenyl benzoate, benzyl benzoate, methyl p-toluate, ethyl anisate (that is, other than carboxyl group). Examples of the aromatic moiety include, in addition to the phenyl group, lower alkyl- or lower alkoxy-substituted phenyl) and the like.

Among these ester compounds, preferred are carboxylic acid esters, and particularly preferred are aromatic carboxylic acid esters.

The amount of the ester compound added is such that the ratio of the amount of the ester compound and the organoaluminum compound [ester compound / organoaluminum compound (molar ratio)] is usually 0.1 to 2.0, preferably 0.15 to 1.5. , And more preferably 0.2 to
The amount is 1.0. The added amount of the ester compound also means the existing amount of the ester compound in the polymerization step. That is, the effect of the present invention cannot be obtained by carrying out the polymerization step (1) in the presence of the ester compound within the addition amount of the above ester compound, but in the polymerization step (1), a small amount, for example, ester compound / organic It is also possible to use aluminum (molar ratio) of 0.05 or less, add an ester compound in the polymerization step (2), and polymerize in the presence of the ester compound in the addition amount of the above ester compound. <Block Copolymerization> (a) Polymerization Step The block copolymerization of the present invention comprises the following steps (1) and (2). In the present invention, "to carry out steps (1) and (2)" means that an additional polymerization step is carried out between steps (1) and (2) or after step (2), if necessary. It means that you can be done. Step (1) In this step, a propylene homopolymer or a propylene / ethylene copolymer having an ethylene content of 5% by weight or less, preferably 3% by weight or less is contained in an amount of 60 to 90% by weight, preferably 65 to 85% by weight based on the total amount of polymerization. This is a step of producing the product in a weight percentage.

When the ethylene content exceeds 5% by weight, the properties of the polymerized slurry are deteriorated and the rigidity of the product is also lowered.

When the production ratio in the step (1) is less than 60% by weight, the property of the polymerized slurry is deteriorated and the rigidity of the product is lowered. On the other hand, when the production ratio in the step (1) exceeds 90% by weight, the impact strength is lowered. Step (2) In step (2), an ethylene / propylene copolymer having an ethylene homopolymer or a propylene content of 30% by weight or less, preferably 20% by weight or less is contained in an amount of 10 to 40% by weight, preferably 15% by weight based on the total polymerization amount. ˜35 wt%, a step of producing.

When the propylene content exceeds 30% by weight,
The properties of the polymerized slurry are deteriorated and the moldability is also deteriorated.

If the production ratio in the step (2) is less than 10% by weight, the impact strength is lowered. On the other hand, when the production ratio in the step (2) exceeds 40% by weight, the property of the polymerized slurry is deteriorated and the rigidity of the product is also lowered.

MF of the block copolymer obtained in the present invention
R depends on the field of application and the molding method, but is usually 0.1 to 1
It is 00 g / 10 minutes. Polymerization method The method for producing the propylene block copolymer according to the present invention is
It can be carried out by either a batch method or a continuous method. At this time, a method of carrying out the polymerization in an inert hydrocarbon solvent such as heptane, a method of using the used monomer itself as a medium, and a method of carrying out the polymerization in a gaseous monomer without using the medium. , And a method combining these can be adopted.

The polymerization temperature is usually 40 to 90 ° C, preferably 50 to 80 ° C. Polymerization pressure is usually 1 to 50 kg /
It is cm ² G. (B) Addition of ester compound The method for producing a propylene block copolymer according to the present invention is
At any time after the end of the polymerization in step (1), the ester compound is added and at least part of step (2) is carried out in the presence thereof. That is, the ester compound is
When the polymerization in the step (1) is completed, after the completion of the polymerization in the step (1) before the start of the step (2), during the polymerization in the step (2), etc., it can be added to the polymerization tank at any stage, A particularly preferable time for adding the ester compound is when the polymerization in step (1) is completed.

The ester compound may be added in the above-mentioned amount all at once or in divided portions.

[0047]

Examples Example 1 1) Preparation of catalyst To a three-neck glass flask (a thermometer, a dropping funnel and a stirring bar) made of nitrogen and having an inner volume of 500 ml, 144 ml of purified heptane and 58 ml of titanium tetrachloride were added. The dropping funnel was charged with 120 ml of heptane and 66 ml of diethylaluminum chloride. The flask was cooled to -10 ° C, and diethylaluminum chloride was added dropwise over 3 hours under stirring at 120 rpm. After further reacting at -10 ° C for 1 hour, the system temperature is slowly raised to 65 ° C for 1 hour.
The temperature was raised to ° C. After reacting at 65 ° C. for 1 hour, the supernatant was separated by decantation and washed 5 times with 200 ml of fresh purified heptane. Next, 250 ml heptane and 99 ml diisoamyl ether were added, and the mixture was mixed at 35 ° C for 1 hour.
Reacted for hours. After completion of the reaction, the product was washed with 200 ml of purified heptane 5 times in the same manner as in the reduction of titanium tetrachloride. Next, 150 ml of heptane and 116 ml of titanium tetrachloride were added and reacted at 65 ° C. for 2 hours. After completion of the reaction, the product was washed 5 times with 200 ml of purified heptane. Finally, 150 ml of heptane and 2.3 ml of n-butanol were added, reacted at room temperature for 1 hour, and washed with 200 ml of heptane three times to obtain a titanium trichloride composition as a solid catalyst component.

2) Polymerization After the stirring autoclave having an internal volume of 200 liters was sufficiently replaced with propylene, 63 liters of sufficiently dehydrated and deoxygenated n-heptane was introduced, and 50 g of diethylaluminum chloride and 10 g of the titanium trichloride composition. 6
It was introduced under a propylene atmosphere at 5 ° C. The first stage polymerization is
After heating the autoclave to 70 ° C, the hydrogen concentration was adjusted to 10
It was started by introducing propylene at a flow rate of 9 kg / h while adjusting to vol%.

After 180 minutes, the introduction of propylene was stopped and the polymerization was continued at 70 ° C. for 90 minutes. The propylene in the gas phase was purged to 0.4 kg / cm ² G.

Next, 30 ml of n-butyl benzoate was added to the polymerization tank. In the second-stage polymerization, after cooling the autoclave to 65 ° C, ethylene was introduced at a rate of 3.4 kg / hour to obtain 12
It was carried out for 0 minutes.

The slurry thus obtained is filtered,
After drying, a powdery propylene block copolymer was obtained. The physical properties of the product were evaluated as follows. The results are as shown in Table 1. (1) MFR MFR was measured according to ASTM-1238. (2) Ethylene content The ethylene content in the product was measured by IR. (3) Solvent-soluble content (APP) byproduct rate (%) (4) Practical evaluation of physical properties The following additives were added to the powdery polymer, pelletized by an extruder under the same conditions, and a sheet having a thickness of 4 mm was prepared by an injection molding machine to evaluate physical properties. Additive 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 Co.) 0.10% by weight Various physical property measurements The physical properties were measured by the following methods. (A) Flexural modulus: ASTM-D790 (B) Izod impact strength (0 ° C) ASTM-D256 (with notch) (C) Spiral flow measurement method Cross section using a famous machine SJ type (inline screw type) injection molding machine Was measured under the following conditions with a 2 mm × 8 mm mold. Molding temperature: 240 ° C. Injection pressure: 800 kg / cm ² Mold temperature: 40 ° C. Injection rate: 50 g / sec Comparative Example 1 1) Catalyst preparation The same procedure as in Example 1 was carried out. 2) Polymerization Polymerization was performed in the same manner as in Example 1 except that n-butyl benzoate was not added. The results are as shown in Table 1. Comparative Example 2 In the polymerization, the addition timing of n-butyl benzoate was changed to the first
A polymerization operation was performed in the same manner as in Example 1 except that the change was made after the completion of the stage polymerization and before the start of the first stage polymerization. as a result,
The catalyst activity in the first-stage polymerization was low, and the polymerization pressure became too high to continue the polymerization. In the polymerization of Examples 2 and 3 , the polymerization operation was performed in the same manner as in Example 1 except that the addition amount of n-butyl benzoate was changed. The results are as shown in Table 1. In Examples 4 to 7, polymerization was performed in the same manner as in Example 1 except that the ester compound shown in Table 2 was used instead of n-butyl benzoate. The results are as shown in Table 2. In Example 8 and Comparative Examples 3 to 5, except that the monomer feed ratio in the first-stage polymerization and the second-stage polymerization and the ethylene / propylene feed ratio in the second-stage polymerization were changed as shown in Table 3. Was polymerized in the same manner as in Example 1. The results are as shown in Table 3.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

EFFECTS OF THE INVENTION According to the present invention, a propylene block copolymer having an excellent balance of rigidity and impact strength and good moldability can be obtained, and a solvent-soluble by-product can be obtained while maintaining catalytic activity. As described above in the section "Summary of the Invention", it is possible to suppress the generation of.

[Brief description of drawings]

FIG. 1 is intended to help understanding of the technical content of the present invention regarding a Ziegler catalyst.

Claims (1)

[Claims] 1. A method for producing a propylene block copolymer by carrying out the following steps (1) and (2) in the presence of a catalyst comprising a titanium trichloride composition and an organoaluminum compound, said method comprising: After the completion of the polymerization in the step (1), 0.1 to 2.0 of the ester compound is added in a quantitative ratio [ester compound / organoaluminum compound (molar ratio)] with the organoaluminum compound present in the polymerization system, A method for producing a propylene block copolymer, which comprises carrying out at least a part of the step (2) in the presence thereof. Step (1) Propylene homopolymer or propylene / ethylene copolymer having an ethylene content of 5% by weight or less is used in an amount of 60 to 9 based on the total polymerization amount.
Producing 0% by weight. Step (2) Ethylene homopolymer or propylene content is 30% by weight
The following ethylene / propylene copolymer was used in a total polymerization amount of 10
~ 40 wt% producing step.