JPS6312881B2 - - Google Patents

Description

[Detailed description of the invention]

[]Object of the present invention The present invention relates to a method for producing an ethylene polymer having a wide molecular weight distribution. More specifically, a method for producing an ethylene polymer having a wide molecular weight distribution, which comprises polymerizing ethylene with a catalyst system obtained from a hydrocarbon-insoluble solid catalyst component produced by a specific reaction and an organoaluminum compound. Regarding. [] Background of the present invention High-density to medium-density ethylene polymers are widely produced industrially by polymerizing ethylene with a so-called Ziegler catalyst, and are generally used as resin materials for various molded products. . but,
These molded products are increasingly required to have good surface properties. For example, hollow molded products (blow molded products) are required to have no surface roughness (so-called shark skin). However, in ethylene polymers produced using catalyst systems obtained from common transition metal compounds (eg, titanium tetrachloride) and organoaluminum compounds (eg, trialkylaluminium), this surface roughness is generally significant. This phenomenon of surface roughness is related to the molecular weight distribution of the ethylene polymer that is the raw material. That is,
It is believed that the broader the molecular weight distribution of the polymer, the less rough the surface of the molded product will be. The ratio of weight average molecular weight ( ) to number average molecular weight ( ) is used as a measure of the breadth of molecular weight distribution. It is considered that the larger the ratio (that is, /), the broader the molecular weight distribution. Ethylene polymers having this ratio (/) of 10 or more are promising for producing molded products with good surface properties. Ethylene-based polymers with these characteristics have good fluidity, even in the case of polymers with low melt index, and do not cause melt fractures on the surface of molded products, making it possible to produce high-quality blow and film products. It becomes possible to obtain. [] Structure of the present invention Based on the above, the present inventors have searched various ways to produce ethylene polymers having a wide molecular weight distribution, and have found (A) (1) titanium tetrachloride and (2) ( a) Alcohol compounds whose general formula is R-OH, (b) alkoxytitanium compounds whose general formula is Ti(OR) ₄ , and (c)
"Alkoxyaluminum compounds represented by Al(OR) ₃ " (hereinafter referred to as "alkoxy compounds")
A catalyst system obtained from a hydrocarbon-insoluble solid catalyst component obtained by aging a reaction product with at least one compound selected from the group consisting of (B) an organoaluminum compound, in which ethylene alone Alternatively, the inventors have discovered that an ethylene polymer with a wide molecular weight distribution, which is the object of the present invention, can be obtained by polymerizing ethylene and a small amount of α-olefin, thereby achieving the present invention. [] Effects of the present invention (1) Since the catalyst raw material is inexpensive, the catalyst cost is low. (2) Since the activity is high, there is little catalyst residue in the produced polymer, and therefore the catalyst removal step can be simplified or omitted. (3) Because the polymer has a wide molecular weight distribution, it is possible to make products without roughening the surface of the molded product. [] Specific description of the present invention The solid catalyst component used in the present invention is a hydrocarbon-insoluble component obtained by aging a reaction product of titanium tetrachloride and an alcohol compound and/or an alkoxy compound. be. (a) Alcohol Compound The general formula of a typical alcohol compound used to produce a solid catalyst component is shown by the following formula [formula ()]. In the R-OH () () formula, R is

[Formula] (where R ¹ is a hydrogen atom or a saturated or unsaturated aliphatic, alicyclic or aromatic hydrocarbon group having at most 10 carbon atoms, R ² and R ³ is the above-mentioned hydrocarbon group.) Typical examples of these alcohol compounds include isopropyl alcohol, tertiary-butyl alcohol, secondary-butyl alcohol, 1-
Buten-3-ol, tertiary-amyl alcohol, secondary-amyl alcohol, diethyl carbinol, 3-methyl-1-buten-3-ol, 2-heptanol, 3-heptanol, 4
-heptanol, tertiary-heptanol, 2-
Octanol, diisobutylcarbinol, phenylethanol, 1-phenyl-1-propanol, 1-phenyl-2-propanol, 2
-phenyl-2-propanol and the like. In carrying out the present invention, it is desirable that R in the above formula () has 20 or less carbon atoms. (b) Alkoxy compounds Among the alkoxy compounds used to produce solid catalyst components, the general formula of typical alkoxy titanium compounds is shown by the following formula [formula ()]. . In the formula Ti(OR) ₄ () (), R is represented by R above. Representative examples of the alkoxy titanium compounds include alkyl titanates corresponding to the alcohol compounds mentioned above. Furthermore, the general formula of typical alkoxyaluminum compounds is shown by the following formula [formula ()]. In the formula Al(OR) ₃ () (), R is represented by R above. Representative examples of the alkoxyaluminum compounds include alkyl alkonates corresponding to the alcohol compounds mentioned above. (c) Aging ratio The ratio of titanium tetrachloride to the alcohol compound and/or alkoxy compound is generally 0.1.
~1.0, particularly preferably 0.5 to 1.0. If this ratio is less than 0.1, titanium tetrachloride is wasted, which is not economical. On the other hand, if it is 1.0 or more, it is not practical because the polymerization activity of the resulting catalyst system decreases. (d) Aging conditions When titanium tetrachloride is reacted with an alcohol compound or the alkoxy titanium compound, the general formula is TiCl _o (OR) _4-o (where n is 1).
Compounds shown in ~3) are said to be produced. Such compounds are soluble in ordinary organic solvents, but only if R in the formulas (), (), and () is secondary or tertiary.
When aged as described below, a solid is produced that is insoluble in hydrocarbons. Although the structure of this solid is not clear, the compound whose general formula is TiCl _o (OR) _4-o and this solid are related to solubility in the organic solvent, amount of gas generated during reaction, elemental analysis results, etc. From this, it can be confirmed that the two are different. Even if the compound represented by TiCl _o (OR) _4-o is used as a catalyst component,
As is clear from Comparative Example 1, it is not possible to obtain an ethylene polymer with a wide molecular weight distribution. On the other hand, when the hydrocarbon-insoluble solid of the present invention is used, an ethylene polymer with a wide molecular weight distribution can be obtained. The aging temperature and time vary depending on the type of alcohol compound and alkoxy compound and their proportions, but are generally room temperature to 150°C and 10 minutes to 3 hours, particularly 40 to 100°C and 30 minutes to 3 hours. 2 hours is recommended.
If the aging temperature and time are lower than the above, a catalyst system that exhibits sufficient effects cannot be obtained. on the other hand,
Above these, there is no particular merit and it is uneconomical. A solvent is not necessarily required for this ripening. This means that if titanium tetrachloride is added to the extent that it can be stirred and transferred (titanium tetrachloride also serves as a solvent), a solid catalyst component can be produced without adding another solvent (the titanium tetrachloride described above can also be used as a solvent). The ratio of R groups to 1 atomic equivalent is set to about 0.1 to 0.3). but,
Instead of excess titanium tetrachloride, aliphatic hydrocarbons such as n-hexane, n-heptane, octane, nonane, n-paraffin and halogenated hydrocarbons such as trichlene, trichloroethane, tetrachloroethane are preferably used. . The solid catalyst component obtained as described above may be used as a polymerization catalyst component as it is after being subjected to a washing treatment as described below. Furthermore, further effects can be exhibited by reducing using an organoaluminum compound. (e) Reduction reaction Among the organic compounds used in this reduction reaction, the general formula of typical ones is shown below [()
The following formula can be mentioned. AlR ⁴ _o X _3-o () In the formula, R ⁴ represents an alkyl group having at most 6 carbon atoms, X represents a halogen atom, and n is 1, 1.5, 2 or 3. AlR ₃ includes trimethylaluminum,
Mention may be made of triethylaluminum, tri-n-propylaluminium, tri-isopropylaluminium, tri-n-butylaluminum, tri-isobutylaluminum and trihexylaluminum. AlR ₂ Examples include diethylaluminum monobromide. Examples _of AlR _1.5 AlRX ₂ includes methylaluminum dichloride, methylaluminum dibromide,
Mention may be made of ethylaluminum dichloride, ethylaluminum dibromide, n-propylaluminum dichloride, isopropylaluminum dichloride, n-butylaluminum dichloride, isobutylaluminum dichloride and n-pentylaluminum dichloride. In addition to the organoaluminum compounds mentioned above, the organoaluminum compounds used in this reduction reaction include tetraalkyldialmoxane obtained by treating 1 mol of the general formula AlR ₃ (trialkylaluminum) with 0.5 mol of water; Various organoaluminum compounds containing chlorine and/or hydrogen derivatives and inorganic acid groups such as amide or nitrile or sulfuric or phosphoric acid groups can also be used. In this reduction reaction, the ratio of aluminum atoms in the organoaluminum compound to one atomic equivalent of titanium atoms in the solid catalyst component is generally at most 50 atomic equivalents, particularly 1 to 10 atomic equivalents.
Atomic equivalents are preferred. Although the reaction temperature in this reduction reaction varies depending on the type of organoaluminum compound, it is generally -40 to 150°C, and preferably -20 to +60°C from the viewpoint of the function of the resulting catalyst system and the reaction rate. Although the reaction time varies depending on the reaction temperature, the reaction ratio of the organoaluminum compound to the solid catalyst component, and the concentration of the organoaluminum compound to the solvent when an inert solvent is used, 15 minutes to 5 hours is generally sufficient. . The reaction of titanium tetrachloride with an alcohol compound and/or an alkoxy compound, its aging, and the reduction reaction of its solid catalyst component with an organoaluminum compound are carried out under an inert atmosphere (e.g., under nitrogen) with air and moisture excluded. ) will be carried out. (f) Post-treatment The solid catalyst component obtained as described above and its reduced product are solids that are insoluble in hydrocarbons. These may be decanted or filtered, thoroughly washed with a hydrocarbon (e.g., n-hexane, n-heptane, n-paraffin), and fed directly to the polymerization system as a slurry, or after drying, they may be powdered. You may also use it.
Furthermore, it may be used in the form of fine powder by pulverization. The solid catalyst component and the reduced product thus obtained have an ocher to brown color. (g) Polymerization The solid catalyst component purified as described above or its reduced product (generally 5 to 100 mg per 1 part inert solvent) is mixed with an organoaluminum compound (1 part inert solvent) in a conventional manner. Homopolymerization of ethylene or ethylene and α- The present invention can be achieved by copolymerizing with olefin. Representative examples of organoaluminum compounds used in polymerization include those shown in the reduction reaction described above. Further, the third component is an electron donating compound,
Those known in the polymerization of ethylene can be used. Inert solvents include unsaturated aliphatic hydrocarbons such as butane, pentane, hexane, heptane, cyclohexane and methylcyclohexane, and aromatic hydrocarbons such as benzene, toluene and xylene. When copolymerizing with ethylene, the α-olefin used must have at most 12 carbon atoms.
-Olefins are common. Particularly desirable are those having 8 or less carbon atoms (for example, propylene, butene-1, 4-methylpentene-1). The ratio of the α-olefin to ethylene is usually 50 mol% or less, and especially when the content of α-olefin in the obtained copolymer is 20 mol%.
It is preferable to copolymerize so that the amount is as follows (in particular, 10 mol% or less). When copolymerizing, random copolymerization or block copolymerization may be performed. In carrying out the method of the present invention, the polymerization temperature and pressure are not particularly limited, and commonly used conditions can be applied, but in general, room temperature to
A temperature range of 300° C. and a polymerization pressure of 1 to 200 atmospheres are employed. If necessary, a molecular weight regulator such as hydrogen, halogenated hydrocarbon or diethylzinc may be present in the polymerization reaction system to control the molecular weight. (h) Post-treatment and use The ethylene polymer obtained as described above has a fairly high polymerization activity, so it can be used after completely removing the inert solvent used in the polymerization. Depending on the purpose, catalyst residue remaining in the polymer may be removed by a known method. The ethylene polymer obtained in the present invention is
As mentioned above, it has a fairly wide molecular weight distribution, so it is promising for use in films and blow molding. [] Examples and Comparative Examples The present invention will now be explained in more detail with reference to Examples. In addition, in the Examples and Comparative Examples, the melt index (MI) was measured according to JIS K-6740. Further, as a measure of molecular weight distribution, / was determined by measurement using gel permeation chromatography (GPC) manufactured by Waters. Example 1 (A) Production of catalyst component (A) A 200 c.c. three-necked flask equipped with a thermometer and a stirrer was sufficiently purged with nitrogen, and 10 ml of trichlene and 5.7 g of titanium tetrachloride were added to the flask. (30 mmol) was added. 1.8 g of isopropyl alcohol [hereinafter referred to as "compound (1)"] (30 mmol) was added to 10 mmol of isopropyl alcohol at room temperature while stirring thoroughly.
It was dripped over a period of minutes. Furthermore, after maintaining the temperature at 40°C for 30 minutes, the reaction system was further heated to 85°C. After 50 minutes had passed since the temperature was raised, solids gradually began to precipitate, and after being maintained at this temperature for 2 hours, it was cooled. After thoroughly washing the insoluble solid with n-hexane, it was dried at a temperature of 40°C under reduced pressure for about 1 hour to obtain 2.5 g.
ocher solid [hereinafter referred to as "catalyst component (A)"]
was gotten. (B) Homopolymerization of ethylene Place the catalyst component (A) obtained in (A) above in a 1.2 autoclave purged with nitrogen (the amount used is shown in Table 2). 1.0 mmol of triisobutylaluminum and 350 g of n-hexane were charged, and the temperature of the polymerization system was raised to 95°C. Furthermore, the partial pressure is 15Kg/
After hydrogen was introduced until the pressure reached cm ² (gauge pressure, the same applies hereinafter), ethylene was introduced until the partial pressure reached 7 Kg/cm ² . Polymerization was carried out for 60 minutes while feeding ethylene to maintain the pressure. After purging ethylene, the product was dried at a temperature of 50° C. under reduced pressure for 1 hour to remove n-hexane.
As a result, a white polymer (polyethylene) was obtained. The bulk density of this polymer was 0.36 g/cc. Table 2 shows the amount of catalyst component (A) used, the yield of the obtained polymer, the (weight average molecular weight) and (number average molecular weight) measured by the GPC method, and/or MI (melt index). Shown below. Example 2 The amounts of trichlene and titanium tetrachloride used in (A) of Example 1 were 25 ml and 12.2 g (65
mmol) and further in place of compound (1),
5.6g of isopropyl titanate [hereinafter referred to as “compound
The heat treatment, washing and drying were carried out in the same manner as in Example 1 (A), except that 20 mmol of the product was used. As a result, 7.2 g of solid was obtained.
4.2 g of this solid, 20 ml n-hexane and 2.4 g
of ethylaluminum sesquichloride (10 mmol) was placed in a 200 ml flask and treated at a temperature of 50° C. for 1 hour. Next, the obtained solid was thoroughly washed with n-hexane and further dried at a temperature of 40°C under reduced pressure for a period of time to obtain 4.0 g of solid (hereinafter referred to as "catalyst component (B)"). It was done. Examples 3 to 8 Titanium tetrachloride was used in the amount shown in Table 1, and the alcohol compound or alkoxy titanate compound was compound (2) and tertiary-butyl titanate [hereinafter referred to as "compound (3)"]. , tertiary-butyl alcohol [hereinafter referred to as "compound (4)"], 2-methyl-3-buten-2-ol [hereinafter referred to as "compound (4)"]
(5)], 2-octyl alcohol (hereinafter referred to as "compound (6)"), or 2-phenyl-2-
Propanol [hereinafter referred to as "compound (7)"] is the first
A catalyst component was prepared in the same manner as in Example 1 (A), except that the amounts shown in the table were used, and then washed and dried. Same as Example 1 (B) except that catalyst component (B) or catalyst component (H) obtained as above was used in the amount shown in Table 2 instead of catalyst component (A). Homopolymerization of ethylene was carried out under these conditions. After the polymerization was completed, purification was carried out in the same manner as in Example 1 (B). The yield of the obtained polymer is shown in Table 2. MI of Example 1 and the polymer obtained above,
Mw and/or are shown in Table 2.

【table】

[Table] 1) ( ) is millimoles

[Table] Example 9 Ethylene and butene-1 were combined under the same conditions as in Example 2, except that the amount of catalyst component (B) used was changed to 40 mg, and 10 g of butene-1 was added as α-olefin. Polymerization was carried out. After the copolymerization was completed, purification was carried out in the same manner as in Example 2. As a result, 143g
A copolymer was obtained. The MI of this copolymer is
0.41g/10min, is 17.1× ¹⁰⁴ ,
n was 1.35×10 ⁴ (i.e. w/n
is 18.9). Also, the density of this copolymer is 0.951g/
It was cc. Comparative Example 1 The amounts of trichlene and titanium tetrachloride used in (A) of Example 1 were reduced to 23 ml and 4.4 ml, respectively.
g (23 mmol), and instead of compound (1),
Heat treatment was carried out in the same manner as in Example 1 (A) except that 1.07 g of ethyl alcohol (23 mmol) was used, but no insoluble solid could be obtained, but at a temperature of 50 °C The solvent was distilled off under reduced pressure,
A pale yellow solid was obtained. Example 1 except that 63 mg of this solid was used instead of the catalyst component (A) used in (B) of Example 1, and the ethylene pressure and hydrogen pressure were changed to 10 Kg/cm ² and 2 Kg/cm ² , respectively. Ethylene polymerization was carried out in the same manner as in (B). As a result, 191g
A polymer was obtained. The MI of this polymer is 0.14
g/10 minutes. Also, w was 14.3×10 ⁴ and n was 1.33×10 ⁴ (i.e.,
w/n is 10.8). Comparative Example 2 Example 4 except that 6.5 g of n-butyl titanate (19 mmol) was used instead of compound (3) used in producing catalyst component (D) of Example 4.
Heat treatment was carried out in the same manner as above. However, it was not possible to obtain an insoluble solid. Example 10 In a 200 ml flask, 50 g of titanium tetrachloride (264 mmol) was kept under reflux in a solution of 9.0 g of aluminum triisopropoxide (44.1 mmol) in 50 ml of n-hexane for 1 hour. After cooling, it was thoroughly washed with n-hexane and dried. As a result, 11.1 g of solid was obtained. In place of the catalyst component (A) used in Example 1 (B), 25.7 mg of the solid obtained above was used, and the partial pressures of hydrogen and ethylene were 7 Kg/cm ² and 10 Kg/cm ^{2 ,} respectively. Ethylene polymerization was carried out in the same manner as in Example 1 (B) except that the As a result, 102
g of polymer was obtained. The MI of this polymer is 0.02
g/10 minutes. Further, w was 25.5×10 ⁴ and n was 1.05×10 ⁴ . That is,
w/Mn is 24.2). Example 11 1.02 g of the catalyst component (B) obtained in Example 2, 60 mmol of triisobutylaluminum, and 60 mmol of n-hexane were charged into a 100 mm autoclave purged with nitrogen. After raising the temperature of the polymerization system to 95°C, hydrogen was introduced until the partial pressure reached 18 kg/cm ² . Next, ethylene was introduced until the partial pressure reached 10 kg/cm ² (supplied to maintain that pressure during ethylene polymerization), and polymerization was continued for 2 hours while supplying butene-1 of 3 in 3 parts. I did it. As a result, 12 kg of polymer (MI 0.2 g/10 minutes) was obtained. 0.2 parts by weight of calcium stearate and 0.1 parts by weight of 2,6-di-tertiary-butyl-P-cresol were added to 100 parts by weight of this polymer, and pellets were formed using an extruder. The obtained pellets were subjected to film molding and blow molding. The surface texture of the obtained molded products was all satisfactory.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of the Ziegler catalyst of the present invention. In this figure, R is a secondary or tertiary hydrocarbon group.

Claims (1)

[Claims] 1 (A) (1) Titanium tetrachloride; (2) (a) an alcoholic compound whose general formula is R-OH; (b) whose general formula is Ti(OR) ₄ The alkoxytitanium compound and (c) general formula are
By aging a reaction product with at least one compound selected from the group consisting of alkoxyaluminum compounds represented by Al(OR) ₃ (where R is a secondary or tertiary hydrocarbon group). (B) an organoaluminum compound; and (B) an organoaluminum compound. Method for producing a polymer.