JPS6312887B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a propylene block copolymer while maintaining fluidity without causing adhesion or bridging between polymer particles. Conventionally, various methods for producing propylene-α-olefin block copolymers have been proposed with the aim of improving impact resistance, low-temperature properties, and the like. For example, a gas phase block copolymerization method is also known in which a propylene polymer is produced in the first stage and one or more other α-olefins are copolymerized with the propylene polymer in the gas phase in the second stage. The method of performing gas phase block copolymerization in the latter stage has many advantages over the method of performing block copolymerization in the presence of an inert hydrocarbon solvent, such as not requiring recovery of the solvent or drying of the polymer. However, the reaction rate of the gas phase block copolymerization method is slow, and furthermore, all of the amorphous polymer produced during polymerization is contained in the polymer.
There are drawbacks such as sticking of polymer particles or powder (hereinafter simply referred to as polymer particles), which may cause various troubles. For this reason, for example, in Japanese Patent Application Laid-Open No. 53-30686,
After polymerizing propylene in the first stage and removing unreacted propylene, ethylene or ethylene and propylene are introduced in the presence of a propylene polymer in the second stage to perform gas phase copolymerization.
RnAlX _3-o (However, R represents an alkyl group or an aryl group, X represents a halogen atom, and n represents 1≦n≦
It has been shown that the reaction rate during block copolymerization can be improved by adding an organoaluminum compound represented by the number 3). However, although this method can improve the reaction rate during block copolymerization,
The adhesion of the produced block polymer particles to each other is significant.
The drawback is that stable operation cannot be achieved. That is,
If polymer particles stick to each other during polymerization, they may not only stick to the walls of the polymerization tank and cause bridging, but also cause blockage of the polymer extraction piping, as well as insufficient removal of polymerization heat, causing the polymer to melt and solidify due to local heat, and even adversely affecting the physical properties of the polymer. It has the disadvantage of having a negative impact. The present inventors investigated a method for copolymerizing α-olefin blocks without the above-mentioned sticking phenomenon, and found that a specific aluminum alkoxide was added to the propylene polymer when polymerizing α-olefin in the gas phase. By doing so, the inventors discovered that block copolymerization can be carried out with no adhesion between polymer particles, good fluidity, and an improved reaction rate, leading to the completion of the present invention. The present invention provides propylene or propylene and other α
- General formula for olefin and titanium trichloride
R″nAlX _3-o (However, in the formula, R″ is an alkyl group or an aryl group, X is a halogen or hydrogen, and n is 1 to 3
) _is polymerized in the presence of a catalyst containing an organoaluminum compound represented by An aluminum alkoxide represented by one group or atom selected from an alkyl group, an aryl group, and a halogen atom, where R' is an alkyl group or an aryl group, and n is an integer of 0, 1, or 2. Add 1
This is a method for producing a propylene block copolymer, which comprises copolymerizing one or more α-olefins in a gas phase. The present invention will be sequentially explained below. In the present invention, the method for producing the propylene polymer may be any gas phase method, solvent method, or solvent-free method as long as it yields a powder or particulate polymer with good fluidity. In addition, in order to efficiently copolymerize α-olefin with propylene polymer in the gas phase, the angle of repose of the propylene polymer is generally 50 degrees or less, especially 30 to 35 degrees.
degree, bulk specific gravity is 0.35g/cc or more, especially 0.4~0.55g/cc
cc, it is preferable to use a particulate polymer having an average particle diameter of 100μ or more, particularly 300μ or more. The polymerization catalysts used to produce such propylene polymers are generally titanium trichloride and the general formula R″nAlX _3-o , where R″ represents an alkyl or aryl group and X represents a halogen or A catalyst consisting of hydrogen and an organoaluminum compound represented by n (n represents a number from 1 to 3) is used.
As the titanium trichloride, conventionally known titanium trichloride can be used, but it is preferable to use titanium trichloride that has been subjected to an activation treatment. For example, titanium trichloride obtained by treating β-type titanium trichloride with a complexing agent and then with titanium tetrachloride; titanium trichloride obtained by pulverizing titanium trichloride with a ball mill; titanium tetrachloride in the presence of ethers; Examples include titanium trichloride which is treated with an organoaluminum compound to form a liquid and which is further heated to form a solid; titanium trichloride supported on a carrier such as a magnesium compound; and the like. Particularly preferred among these titanium trichlorides are highly active titanium trichlorides whose catalyst polymerization rate is at least 2000 g polymer/g.TiCl ₃ /hour. (The polymerization rate referred to here is the rate at which titanium trichloride (TiCl ₃ ) and diethylaluminum monochloride (AlEt ₂ Cl) are at a rate of 2 of TiCl ₃ -AlEt 2 Cl, which gives a molar ratio of AlEt ₂ Cl/TiCl ₃ of ₁₀ . The amount of polypropylene produced per 1 g of TiCl ₃ obtained by polymerizing propylene at a temperature of 65°C for 1 hour in the presence of a base catalyst using propylene itself as a solvent is shown.
A compound represented by R″nAlX _3-o (where R″, , diethyl aluminum hydride, etc. are used. In particular, diethylaluminum chloride is preferably used. The titanium trichloride and organoaluminum compounds shown above are generally organoaluminum compounds/
The molar ratio of titanium trichloride is 1 to 30, preferably 2 to 30.
Used in a range of 15. In the present invention, the above-mentioned catalyst may be used as it is, but it is preferable to use it for the polymerization of propylene or propylene and other α-olefins after pretreatment at once, since the angle of repose of the resulting propylene polymer is small and the bulk specific gravity is high. is particularly preferable because of its large value. The pretreatment is achieved by preliminarily polymerizing a small amount of olefin onto a catalyst consisting of titanium trichloride and an organoaluminum compound. That is,
Titanium trichloride and an organoaluminum compound may be added to an inert solvent such as hexane, heptane, etc., and an olefin such as propylene, ethylene, butene-1, or a mixture thereof may be supplied thereto for polymerization. This pretreatment is generally referred to as prepolymerization, and known polymerization conditions can be used as they are. Polymerization temperature is 30~70℃,
Preferably it is 40-60°C. The polymerization rate is preferably as high as possible per unit weight of titanium trichloride, but it is generally in the range of 1 to 100 g/g.TiCl ₃ from the viewpoint of equipment or economy. Furthermore, a molecular weight regulator such as hydrogen may be added during polymerization. Furthermore, it is preferable that the prepolymerization is carried out uniformly in a batch manner. Note that it is preferable to add a third component to the catalyst made of titanium trichloride and an organoaluminum compound described above. Addition of the third component has the advantage of reducing the angle of repose and increasing the bulk specific gravity of the resulting polymer. The third component is an electron donor, such as
Publication No. 37-210, Publication No. 49-32313, Japanese Unexamined Patent Application Publication No. 1973-
Examples include nitrogen-containing compounds, phosphorus-containing compounds, ether compounds, ester compounds, etc., as described in Publication No. 123182 and the like. In particular, polyethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether can be preferably used. The amount of the third component added is generally 0.0001 to 5, preferably 0.001 to 1 in molar ratio to titanium trichloride.
is within the range of Using the above catalyst components, the polymerization of propylene or propylene with other α-olefins such as ethylene and butene may be carried out in an inert solvent, but preferably in liquid propylene in the presence of a molecular weight modifier.
It is carried out at a temperature of 40-100°C and a pressure of 1-50 Kg/cm ² . The propylene polymer obtained by the above polymerization is prepared by converting the inert hydrocarbon and unreacted monomers into a solid-liquid state when the polymerization is carried out by a solvent polymerization method, or the unreacted monomers by a gas-phase method or a solvent-free polymerization method. It is preferable to remove it using a separator or a flash tank to form propylene polymer particles that are substantially free of volatile matter and maintain catalytic activity. The propylene polymer thus obtained has a shape with good fluidity as described above, and is supplied to the gas phase copolymerization zone in the latter stage of the present invention, where α-olefin is block copolymerized with the propylene polymer in the gas phase. be done. In the present invention, the gas phase copolymerization in the second stage is carried out by supplying at least one gaseous α-olefin in the presence of the propylene polymer particles obtained in the first stage, and at this time aluminum alkoxide is added. It is important to make sure that it exists. Aluminum alkoxide has the general formula RnAl(OR') _3-o (wherein R represents one type of group or atom selected from an alkyl group, an aryl group, and a halogen atom,
R' is an alkyl group or an aryl group, n is 0,
Represents an integer of 1 or 2. ). In the above formula, the alkyl group may be linear or branched, and generally has 20 or less carbon atoms, preferably 8 or less carbon atoms. Specific compound names include dimethylaluminum methoxide, dimethylaluminum ethoxide, dimethylaluminum isopropoxide, diethylaluminium methoxide, diethylaluminium ethoxide,
diethylaluminium-n-butoxide, diethylaluminium-iso-butoxide, diethylaluminium-t-butoxide, diethylaluminium-sec-butoxide, diethylaluminum octoxide, diethylaluminium phenoxide, ethylaluminum diethoxide, diisobutylaluminum ethoxide, These include dipropylaluminum ethoxide, ethylaluminum chloride monoethoxide, ethylaluminum bromide monoethoxide, ethylaluminum chloride monobutoxide, aluminum trimethoxide, aluminum triethoxide, and mixtures thereof. Among these, diethylaluminum ethoxide and diethylaluminum-iso-butoxide are preferably used. In the present invention, the aluminum alkoxide produced by a conventionally known method is used. Usually, an organic aluminum compound represented by the general formula R″nAlX _3-o (where R″ is an alkyl group or an aryl group, X is a halogen or hydrogen, and n is a number from 1 to 3) is combined with an alcohol or Manufactured by reacting with oxygen. The reaction requires simply mixing the two components. For example, in the case of a reaction between an organoaluminum compound and an alcohol, the organoaluminum compound is diluted with an inert hydrocarbon solvent, stirred and cooled, and an alcohol solution diluted with an inert hydrocarbon solvent is dropped into this solution. and, if necessary, by heat treatment. The reaction conditions may be selected such that the molar ratio of organic aluminum/alcohol is in the range of 0.35 to 5, preferably 0.5 to 2. The reaction product is subjected to distillation etc. to separate aluminum alkoxide,
Although it may be used after being purified, it may also be used unpurified as a reaction mixture. In the present invention, the amount of the aluminum alkoxide added is 0.5 to 30 mol, preferably 1 to 15 mol, based on titanium/gram atom contained in the propylene polymer particles. The method of adding the aluminum alkoxide is not particularly limited, but it is generally sprayed onto propylene polymer particles in vapor form or diluted with an inert gas or inert hydrocarbon solvent. In addition, during gas phase copolymerization, in order to improve catalyst activity, the general formula R″nAlX _3-o (wherein R″ is an alkyl group or an aryl group,
A compound represented by (X represents halogen or hydrogen, n represents a number from 1 to 3) may be mixed with the aluminum alkoxide or may be added separately. The addition ratio at this time varies depending on the type of organoaluminum compound, but for example, in the case of diethylaluminum chloride, it is not more than 5 times the mole of alkyl aluminum alkoxide,
Preferably, the molar ratio is 1 times or less, and in the case of triethylaluminum, it is 3 times or less, preferably 0.5 times or less. In the present invention, the α-olefin to be block copolymerized with the propylene polymer is generally an α-olefin having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms, and mixtures thereof. More preferably an ethylene-propylene mixture is used. The conditions for gas phase copolymerization are usually 30 to 100℃ and 1 to 50℃.
Kg/cm ² , and the copolymerization is carried out so that the polymerization ratio of the latter α-olefin block portion to the total polymer is 3 to 50% by weight, preferably 10 to 30% by weight. When using an ethylene-propylene mixed gas, which is a more preferred embodiment, the gas composition is generally 20 to 90 mol% ethylene, preferably 40 to 90 mol%.
It is 80 mol%. The production method of the present invention basically consists of a first stage in which propylene or propylene and α-olefin are polymerized to obtain a propylene polymer, and a second stage in which the propylene polymer is subjected to gas phase copolymerization of α-olefin. However, in the present invention, the subsequent gas phase copolymerization of α-olefin can be carried out in multiple stages, and such a method is also included in the present invention. For example, the following combinations of polymerization steps may be used. (1) A-B (2) A-A'-B (3) A-B-A' (4) A-B-C (5) A-B-C-D A: Propylene or propylene and other Step A' of polymerizing propylene with α-olefin to obtain a propylene polymer: Step B of polymerizing propylene or propylene with another α-olefin in a gas phase in the presence of a propylene polymer: Step B of polymerizing propylene with another α-olefin in the presence of a propylene polymer in a gas phase α− below
Step C of polymerizing olefin: Polymerization step D in which the hydrogen concentration in Step B, polymerization temperature, type or composition ratio of α-olefin, etc. is changed: Hydrogen concentration and polymerization temperature in Step B and C,
Polymerization process in which the type or composition ratio of α-olefin is changed In the combination of the above polymerization processes, aluminum alkoxide may be added in any process except A, which corresponds to the first stage of the present invention. That is,
Alkylaluminum alkoxide may be added at each step after step A' or step B, or may be added for the first time in step C or step D. In the present invention, the equipment used for the gas phase copolymerization in the latter stage is not particularly limited, and equipment such as a fluidized bed or a fluidized bed with a stirring device is preferably used, and the polymerization is carried out continuously or batchwise. After completion of the gas phase copolymerization, the block polymer taken out continuously or batchwise is subjected to inactivation treatment or deashing treatment with alkylene oxide, alcohol, etc., and if necessary, removal of the amorphous polymer with a solvent. As described above, according to the method of the present invention, it is possible to obtain a block copolymer with high activity and excellent impact resistance while maintaining fluidity without causing phenomena such as adhesion during the subsequent gas phase block copolymerization. can. Particularly in a continuous process, extraction of the block copolymer can be carried out smoothly and products with stable quality can be obtained. The present invention will be described below with reference to Examples, but the present invention is not limited thereto. In the examples, the angle of repose, n-heptane extraction residue, MI, and activity were measured by the following methods. Angle of repose From "Powder Physical Properties Measurement Method" (written by Sohachiro Hayakawa), page 97. That is, into a cylindrical container with an inner diameter of 68 mm and a height of 48 mm, which has an outlet with a diameter of 10 mm at the center of the bottom, polymer is dropped from a funnel installed at a height of 50 mm above the cylindrical container, and after filling the cylindrical container, the outlet is opened. The container was opened to allow the polymer in a stationary state to flow out, and the slope of the powder layer remaining in the container was measured as the angle of repose. n-heptane extraction residue Weight % remaining after extracting the polymer with n-heptane for 8 hours in a Rix L-extractor. M I Melt Index (g/10 min) ASTM D-
According to 1238. Activity (second stage) During block copolymerization, 1 per 1 g of titanium trichloride
Number of grams of polymer polymerized in hours (g polymer/g TiCl ₃ hr) Example 1 Brown titanium trichloride obtained by reducing titanium tetrachloride with diethylaluminium monochloride in an inert solvent was After treatment with the same mole of diisoamyl ether at room temperature, it was chemically treated with a 65° C. hexane solution of titanium tetrachloride in an amount of 1.5 times the mole of the brown titanium trichloride to obtain purple titanium trichloride. Ten
Heptane 5 was poured into an autoclave equipped with a stirrer, and 50 g of the titanium trichloride, 0.01 times the mole of diethylene glycol dimethyl ether (diglyme) and 5 times the mole of diethylaluminium monochloride based on titanium trichloride were added, and the temperature was raised. When the temperature reached 50℃, the supply of propylene gas was started. Prepolymerization was carried out for 1 hour while maintaining the temperature at 50°C, and then unreacted propylene monomer was purged to stop the reaction. The amount of polymerization was 14 g per g of titanium trichloride, and a catalyst suspension consisting of propylene polymer and catalyst was obtained. After replacing an autoclave with a stirrer with a capacity of 300 ml with propylene, 200 ml of liquid propylene was added.
The above catalyst suspension (6.0 g in terms of titanium trichloride composition) and diethylaluminum monochloride in an amount of 6 times the mole based on titanium trichloride were added with stirring, and polymerization was carried out at 60°C for 1.5 hours. .
Note that hydrogen was added to adjust the molecular weight, and the gas phase concentration was controlled by gas chromatography to be 6.1 mol% during polymerization. After the reaction was completed, the resulting slurry of propylene homopolymer was transferred from the bottom to a flash tank, where unreacted monomers were purged to obtain catalyst-containing polypropylene particles substantially free of volatile matter. The polymerization ratio (polypropylene (g)/titanium trichloride (g)) is 5000,
The properties of the polypropylene particles were as follows.

Table: A 300 g portion of substantially volatile-free catalyst-containing polypropylene particles polymerized in the manner described above was withdrawn under an argon atmosphere and placed in a two-glass autoclave equipped with a ribbon-type stirrer. In a separate container, triethylaluminum diluted with n-heptane and ethyl alcohol also diluted with n-heptane were reacted in equimolar amounts to form a solution containing diethylaluminum ethoxide at a concentration of 0.5 mmol/ml. An n-heptane solution was prepared. An n-heptane solution of diethylaluminum ethoxide in an amount equivalent to 4 times the mole per gram atom of titanium was sprayed onto the polypropylene particles under an argon atmosphere, and the mixture was further mixed at 60° C. for 10 minutes. After suctioning with a vacuum pump for 5 minutes, the ethylene/propylene = 1/1 that had been prepared in the cylinder was
An ethylene-propylene-hydrogen mixed gas having a molar ratio of 0.4 mol % hydrogen was introduced, and the pressure was set at 3 kg/cm ² gauge pressure. Next, while introducing the amount of ethylene-propylene mixed gas that is consumed in polymerization, 3 kg/
The polymerization was carried out under a cm ² gauge pressure and maintained at 60° C. until the polymerization amount of the block portion was 12% by weight of the final polymer. After polymerization, purge unreacted gas and reduce to 10% by weight.
of water at 70°C for 30 minutes. Polymerization activity and obtained propylene
The properties of the ethylene block copolymer are shown in Table 1. Comparative Example 1 Instead of diethyl aluminum ethoxide,
The same procedure as in Example 1 was carried out except that diethylaluminum chloride was used. Results first
Also listed in the table. Comparative Example 2 The same procedure as in Example 1 was carried out except that triethylaluminum was used instead of diethylaluminum ethoxide. The results are also listed in Table 1. Comparative Example 3 Instead of diethyl aluminum ethoxide,
The same procedure as in Example 1 was carried out except that triethylaluminum was added in an amount equivalent to 1.7 mol per gram atom of titanium. The results are also listed in Table 1.

[Table] *Number of moles of organoaluminum compound added per 1 gram atom of titanium According to the angle of repose in Table 1 and visual observation, when diethylaluminum ethoxide of Example 1 was added, the polymer particles during polymerization No adhesion or adhesion to the autoclave wall was observed. Furthermore, when diethylaluminium chloride of Comparative Example 1 was added, the fluidity was good, but the polymerization activity was low. Furthermore, comparative examples 2 and 3
When triethylaluminum was added, the adhesion of polymer particles to each other was severe, and adhesion to walls and bridging occurred. Example 2 The procedure of Example 1 was repeated, except that the diethylaluminum ethoxide of Example 1 was replaced with an ethylaluminum ethoxide mixture prepared by changing the molar ratio of ethyl alcohol (EtOH) and triethylaluminum (Et ₃ Al). Polymerized in the same way. The results are shown in Table 2.

[Table] As is clear from Table 2, No.1 and No.2
When the molar ratio of EtOH/Et ₃ Al≧1, the fluidity is very good. In addition, in No. 3 and No. 4, which are considered to be mixed with diethylaluminum ethoxide in a free state of triethylaluminum, the activity increases, but the reactivity slightly decreases. However, there were no problems under operating conditions such as stirring, and this was more advantageous than the case where triethylaluminum was added alone. Example 3 The same procedure as in Example 1 was carried out except that alkyl aluminum alkoxides produced by changing the types of organoaluminum compounds and alcohols were used. The results are shown in Table 3.

[Table] As is clear from Table 3, liquidity is good in all cases. Furthermore, triethylaluminum is particularly preferred as the organoaluminum compound. Example 4 Polymerization was carried out in the same manner as in Example 1, except that diethylaluminium ethoxide was used in 5 times the mole per 1 gram atom of titanium, and the gas phase block copolymerization conditions were as shown in Table 4. . A polymer with good fluidity was obtained, and its properties are shown in Table 4. Comparative Examples 4 and 5 In Example 1, a mixture of diethylaluminum chloride and triethylaluminum at a molar ratio of 3:2 (comparative example 4) and diethylaluminium chloride (comparative example 5) were used instead of diethylaluminium ethoxide, and Polymerization was carried out in the same manner as in Example 1, except that the phase block copolymerization conditions were as shown in Table 4. These results are also listed in Table 4.

[Table] Number of grams of block part *Amount of polymerization =

Claims (1)

[Claims] 1 Propylene or propylene and other α-olefins are combined with titanium trichloride and the general formula R″nAlX _3-o (however,
In the formula, R'' is an alkyl group or an aryl group, X is a halogen or hydrogen, and n is a number from 1 to 3. , then in the presence of the propylene polymer the general formula RnAl
(OR') _3-o (However, R is one type of group or atom selected from an alkyl group, an aryl group, and a halogen atom, R' is an alkyl group or an aryl group, and n is 0, 1, or 2. 1. A method for producing a propylene block copolymer, which comprises adding an aluminum alkoxide represented by (an integer) and copolymerizing one or more α-olefins in a gas phase.