JPH0323086B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a crystalline propylene random copolymer with excellent randomness. More specifically, the present invention relates to a method for producing a random copolymer suitable for film use, which has easy heat-sealability, large bulk density, and excellent fluidity, with high catalyst efficiency and good operability. [Prior Art] Crystalline propylene/ethylene random copolymers containing a small proportion of ethylene are processed into various films, hollow bodies, injection molded products, etc., and are widely used. In particular, in the film field, it is widely used as a variety of packaging materials because it has better heat sealability than propylene homopolymer. However, the propylene/ethylene random copolymers that have been provided so far cannot necessarily be said to have sufficiently high impact strength, nor can they be said to have sufficient heat sealability. In order to improve this, when trying to increase the ethylene content and obtain a propylene/ethylene random copolymer with high impact strength, relatively low melting point, and excellent heat sealability, it tends to become sticky, which hinders the polymerization operation. Propylene/ethylene random copolymers with an ethylene content of more than 5 mol % are not commercially available because they often result in a product with poor commercial value. [Problems to be Solved by the Invention] As a result of various studies in order to obtain a random copolymer with even better properties, the present inventors found that a random copolymer having the same ethylene content or the same melting point that had been used in practical use in the past We have now discovered a method for producing a random copolymer that has superior physical properties such as transparency and heat sealability, as well as improved impact strength, as compared to propylene/ethylene random copolymers. Therefore, an object of the present invention is to develop a propylene/α-olefin random copolymer with excellent catalytic effect, which has excellent transparency, heat sealability, impact resistance, etc., and which exhibits less stickiness when formed into a film. Another object of the present invention is to provide a manufacturing method with good operability. Another object of the present invention is to solve the problem of propylene α-
An object of the present invention is to provide an improved method for producing a powdered copolymer in the production of an olefin random copolymer. [Means for Solving the Problems] According to the method of the present invention, (A) a solid titanium catalyst component containing an interaction product of a magnesium compound, a titanium compound, and an electron donor as essential components; (B) an organoaluminum compound When producing a crystalline propylene random copolymer by copolymerizing propylene and another α-olefin in the presence of a catalyst formed from a catalyst component and (C) an electron donor catalyst component, component (B) By supplying a gaseous oxygen-containing compound at a ratio of 0.0001 to 0.5 mol per gram of aluminum atom in standard conditions, the formed film has excellent transparency, heat sealability, impact resistance, etc. A crystalline propylene tendon copolymer that can provide a film with less stickiness and stickiness can be produced with high catalytic efficiency and with good operability. Solid titanium catalyst component (A) containing as an essential component an interaction product of a magnium compound, a titanium compound, and an electron donor used in the copolymerization of the present invention
For example, by reacting a magnesium compound (or magnesium metal), a titanium compound, and an electron donor in any order, or by using a reaction aid such as a halogenating agent and/or an organoaluminum compound in addition to the above raw materials. It can be obtained by a method of reacting in any order, or by a method of further washing the products obtained by each of the above methods with a solvent. This type of catalyst component, in the absence of an inert diluent, typically has a specific surface area of 3
m ² /g or more, for example 30 to 1000 m ² /g,
Halogen/Ti (atomic ratio) is, for example, 4 to 100,
Preferably 6 to 70, Mg/Ti (atomic ratio) for example 2 to 100, preferably 4 to 70, electron donor/methane (molar ratio) for example 0.2 to 10,
It is preferably in the range of 0.4 to 6, and is usually in a highly amorphous state compared to commercially available magnesium halides. Typical examples of the electron donor are esters, ethers, acid anhydrides, alkoxy silicon compounds, and the like. Many methods for producing the titanium catalyst component as described above are already known and can be used in the present invention. As a titanium catalyst component, it also has a narrow particle size distribution.
Preferably, it is spherical, ellipsoidal, or similar in shape. Examples of the organoaluminum compound catalyst component (B) that can be used in the present invention include compounds having at least one Al-carbon bond in the molecule, such as (1)-general formula R ¹ mAl(OR ² ) _o HpXq (Here, R ¹ and R ² are hydrocarbon groups containing carbon atoms, usually 1 to 15, preferably 1 to 4, and may be the same or different from each other. X is halogen, m is 0 <m≦3, 0≦n<3, p is 0≦
p<3, q is a number of 0≦q<3, and m
+n+p+q=3), (2) Group metals represented by the general formula M ¹ AlR ¹ ₄ (where M ¹ is Li, Na, K, and R ¹ is the same as above) Examples include complex alkylated products of and aluminum. Examples of organoaluminum compounds belonging to the above (1) include the following. General formula R ¹ mAl(OR ² ) _3-n (where R ₂ and R ² are the same as above. m is preferably a number of 1.5≦m≦3), general formula R ¹ mAlX _3-n ( Here, R ¹ is the same as above. X is halogen, n
is preferably 0<m<3. ), general formula R ¹ mAlH _3-n (where R ¹ is the same as above, m is preferably 2
≦m<3. ), general formula R ¹ mAl(OR ₂ ) _o X _q (where R ¹ and R ² are the same as above.
Examples include those expressed as m+n+q=3. Among the aluminum compounds belonging to (1), more specifically, trialkyl aluminum such as triethyl aluminum and tributyl aluminum,
In addition to trialkenylaluminums such as triisoprenylaluminum, dialkylaluminum alkoxides such as diethylaluminum ethoxide, dibutylaluminum butoxide, alkylaluminum sesquialkoxides such as ethylaluminum sesquiethoxide, butylaluminum sesquibutoxide, R ¹ _2.5 Al ( OR ² ) Partially alkoxylated alkyl aluminum halogenides, such as diethylaluminum chloride, dibutyl aluminum chloride, diethylaluminium bromide, ethyl aluminum sesquichloride, butyl aluminum sesquichloride, with an average composition expressed as _0.5 , etc. , partially halogenated alkyl aluminum, diethylaluminium hydride, alkyl aluminum sesquihalogenides such as ethyl aluminum sesquibromide, alkyl aluminum dihalides such as ethyl aluminum dichloride, propyl aluminum dichloride, butyl aluminum dibromide, etc. ,
Dialkyl aluminum hydrides such as dibutyl aluminum hydride, partially hydrogenated alkylaluminums such as alkyl aluminum dihydrides such as ethyl aluminum dihydride, propyl aluminum dihydride, ethyl aluminum ethoxy chloride, butyl aluminum butoxy chloride, ethyl aluminum ethoxy Partially alkoxylated and halogenated alkyl aluminums such as bromide. Compounds belonging to (2) above include LiAl
Examples include (C ₂ H ₅ ) ₄ and LiAl(C ₇ H ₁₅ ) ₄ . Further, as a compound similar to (1), it may be an organic aluminum compound in which two or more aluminum atoms are bonded via an oxygen atom or a nitrogen atom. Examples of such compounds include (C ₂ H ₅ ) ₂ AlOAl(C ₂ H ₅ ) ₂ , (C ₄ H ₉ ) ₂ AlOAl
( _C4H9 ) _{2 ,}

〔Effect of the invention〕

According to the present invention, it is possible to obtain a crystalline propylene random copolymer that has a low melting point and good heat-sealability even if the copolymerization component α-olefin is contained in a small amount. Such copolymers have impact resistance,
It also has excellent blocking resistance. The copolymer powder obtained by polymerization has a high bulk density and good fluidity. Furthermore, there is little adhesion of polymers to each other or adhesion to walls during polymerization, and long-term continuous operation is possible. [Example] Example 1 [Preparation of titanium catalyst component (A)] 7.14 g (75 mmol) of anhydrous magnesium chloride and 37 ml (225 mmol) of decane were subjected to a heating reaction at 130°C for 2 hours to form a homogeneous solution. 1.67 g (11.3 mmol) of phthalic anhydride is added to the mixture, and the mixture is stirred and mixed at 130° C. for an additional hour to dissolve phthalic anhydride into the homogeneous solution. After the homogeneous solution thus obtained was cooled to room temperature, the entire amount was dropped over 1 hour into 200 ml (1.8 mol) of titanium tetrachloride maintained at -20°C. After charging, the temperature of this mixture was raised to 110°C over 4 hours, and when it reached 110°C, 18.8 mmol of diisobutyl phthalate was added.
From this point on, the mixture was maintained at the same temperature for 2 hours with stirring. After the completion of the 2-hour reaction, the solid portion was collected by heating, and after resuspending this solid portion in 275 ml of TiCl ₄ , the heating reaction was performed again at 110° C. for 2 hours. After the reaction is complete,
Collect the solid portion by heating again, and thoroughly wash with decane at 110°C and decane at room temperature until no free titanium compound is detected in the washing liquid. The titanium catalyst component (A) synthesized by the above production method is stored as a decane slurry, and a portion of this is dried for the purpose of investigating the catalyst composition. The composition of the titanium catalyst component (A) obtained in this way was 2.1% by weight of titanium;
The contents were 58.0% by weight of chlorine, 18.0% by weight of magnesium, and 12.7% by weight of diisobutyl phthalate. The specific surface area was 210 m ² /g. The titanium catalyst component (A) was a granular catalyst with an average particle size of 13μ and a geometric standard deviation (σg) of particle size distribution of 1.2. [Prepolymerization] 0.4 mmol of the Ti catalyst component described above in terms of Ti atoms is suspended in 200 ml of hexane. After adding 4 mmol of triethylaluminum and 0.8 mmol of diphenyldimethoxysilane, and supplying 2.73 g of propylene over 1 hour while maintaining the temperature at 20°C,
A prepolymerized Ti catalyst component was obtained by replacing the supernatant with sufficiently fresh hexane. [Polymerization] Hexane 0.75 in an autoclave with an internal volume of 2
and fully substituted with propylene at room temperature. 0.75 mmol of triethylaluminum, 0.075 mmol of diphenyldimethoxysilane, and the above-mentioned Ti catalyst component are added in an atom system of 0.015 mg in terms of Ti atoms. After adding 0.15 mmol of oxygen into the system, 100 Nml of hydrogen was charged, and the temperature of the system was immediately raised to 60°C, where a propylene/ethylene mixed gas (91.9/8.1 mol/
mol). A mixed gas was supplied to maintain a total pressure of 2.5 Kg/m ² G, and the entire amount of polymerization for 1.5 hours was precipitated in a large amount of methanol to obtain a polymer. The yield of polymer was 153.3g. Also, the MFR of the polymer is 4.2g/10min, and the ethylene content is 5.2mol.
%, the melting point by DSC was 132°C, the residual rate after extraction with boiling hexane was 94.8 wt%, and the amount of n-decane soluble portion was 6.5 wt%. Comparative Example 1 Polymerization was carried out using the Ti catalyst component of Example 1 without adding oxygen. The yield of polymer was 202.7g. Also, the MFR of the polymer is 4.7g/10min, and the ethylene content is 4.5mol.
%, melting point by DSC is 138℃, boiling hexane extraction residual rate is 93.5wt%, amount of n-decane soluble portion is 7.5wt
%, which shows that the addition of oxygen increases the production rate of a crystalline random copolymer with excellent randomness. Examples 2 and 3 Polymerization was carried out in the same manner as in Example 1 except that 0.15 mmol of oxygen was replaced with 0.10 mmol and 0.15 mmol of carbon dioxide, respectively. The results are shown in Table 1.

[Preparation of titanium catalyst component]

83.6 ml of decane solution containing 50 mmol of ethylbutylmagnesium and 2-ethylhexyl alcohol
23.1 ml (150 mmol) was heated at 80°C for 2 hours to form a homogeneous solution. 1.4 ml of ethyl benzoate was added to this solution to make a sufficiently homogeneous solution. Add dropwise to titanium chloride with stirring over 1 hour. After the completion of the dropwise addition, the mixture was heated to 90°C over 1.5 hours, at which time 1.8 ml of ethyl benbrozoate was added, and the mixture was further kept under stirring for 2 hours at 90°C, after which the solid portion was filtered off. Collect,
This was resuspended in 200 ml of titanium tetrachloride, and
After carrying out a heating reaction at .degree. C. for 2 hours, a solid material is collected by filtration, thoroughly washed and dried with purified hexane until no free titanium compound is detected in the washing solution, and a titanium catalyst component is obtained. The ingredients are titanium 2.8% by weight, chlorine 61% by weight, magnesium
The catalyst component (A) contained 20% by weight and 13.8% by weight of ethyl benzoate, and the catalyst component (A) was a granular catalyst with an average particle size of 13μ and a geometric standard deviation (σg) of the particle size distribution of 1.4. The specific surface area was 180 m ² /g. [Prepolymerization] A flask is charged with 0.4 mmol of the Ti catalyst component described above in terms of Ti atoms and 200 ml of hexane.
A further 0.4 mmol of triethylaluminum is added. 2.1 g of propylene was fed over 1 hour while maintaining the temperature at 20°C. The supernatant was thoroughly removed by decantation using hexane. [Polymerization] An autoclave with an internal volume of 2 is sufficiently replaced with propylene. Propylene/butene-1 (500 g, molar ratio 75/25) was added to the system, and 1 mmol of triethylaluminum and methyl paratoluate were added.
0.3 mmol and the titanium catalyst component described above are added in an amount of 0.002 mg in terms of atoms. After adding 0.01 mmol of oxygen into the system, 3000 Nml of hydrogen was introduced at 70℃.
and stirred for 1 hour. The residual monomer was removed by evaporation to obtain a polymer. Polymer yield is 59
g, apparent specific gravity is 0.30g/ml, MFR is 2.6g/10
The butene-1 content was 8.1 mol%, the melting point was 131°C, and the amount of decane soluble portion was 2.4 wt%. Comparative Example 2 Copolymerization of propylene and ethylene was carried out in the same manner as in Example 1 except that the amount of oxygen added was changed from 0.15 mmol to 0.7 mmol. The yield of polymer was 88.7g. Also, polymer
MFR is 8.9g/10min, ethylene content is 5.3mol%,
The melting point by DSC was 143°C, the residual rate after extraction with boiling hexane was 90.4%, and the amount of n-decane soluble portion was 10.0 wt%.

[Brief explanation of the drawing]

FIG. 1 is a flowchart schematically showing the method of the present invention.

Claims (1)

[Scope of Claims] 1 (A) a solid titanium catalyst component containing an interaction product of a magnesium compound, a titanium compound, and an electron donor as essential components, (B) an organoaluminium compound catalyst component, and (C) an electron donor catalyst When producing a crystalline propylene random copolymer by copolymerizing propylene and other α-olefins in the presence of a catalyst formed from component (B), the amount of gas per 1 g atom of aluminum in component (B) is A method characterized in that an oxygen-containing compound is supplied to the copolymerization system at a ratio of 0.0001 to 0.5 mol.