JP3364894B2 - Method for producing flexible polypropylene - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft material which is excellent in processability, transparency, impact resistance and heat resistance and which is less sticky even when formed into a sheet or film. The present invention relates to a method for producing polypropylene. BACKGROUND OF THE INVENTION Polypropylene is widely used in industrial parts, sheets and films, etc. because of its excellent moldability, rigidity and heat resistance. However, polypropylene having high crystallinity, which is excellent in rigidity and heat resistance, has a disadvantage that it is inferior in impact resistance and transparency. Means for improving these are also widely known. For example, in order to impart impact resistance, a method of randomly copolymerizing propylene with another α-olefin, for example, ethylene, 1-butene, or the like, or a method of copolymerizing propylene and ethylene and then copolymerizing propylene with ethylene after block copolymerization. A method for producing a polymer is known. However, when a random copolymer is used, the impact resistance and the transparency are improved, but the melting point is remarkably reduced, so that the heat resistance is impaired. On the other hand, when a block copolymer is used, it is excellent in impact resistance and heat resistance, but has a drawback that transparency is significantly reduced. On the other hand, attempts to solve the above problems by reducing the stereoregularity of polypropylene have already been proposed. For example, JP-A-59-122506 discloses a polypropylene having a wide molecular weight distribution and low stereoregularity. The stickiness was not yet satisfactory. As described above, polypropylene satisfying transparency, impact resistance, heat resistance and stickiness has not yet been obtained, and its development has been desired. The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, melted polypropylene having a specific molecular weight and stereoregularity in the presence of an organic peroxide. It has been found that the purpose of the present invention can be achieved by kneading, and the present invention has been completed. That is, according to the present invention, the weight average molecular weight is 100
A method for producing a soft polypropylene, comprising melting and kneading a polypropylene having a p-xylene soluble content of 5 to 30 wt% at room temperature in the presence of an organic peroxide. As the polypropylene used in the present invention, known polypropylenes can be used without any limitation, but a homopolymer of propylene or a random copolymer of propylene with up to 5 mol% of other α-olefins is used in the present invention. It is preferably used for the purpose of. Examples of other α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 4-methyl-1-pentene, and the like. [0007] The polypropylene used in the present invention must have a weight average molecular weight of 1,000,000 or more as measured by gel permeation chromatography (GPC). When the weight average molecular weight is less than 1,000,000, not only the transparency of polypropylene obtained by melt-kneading with an organic peroxide is inferior, but also the quality such as stickiness and blocking when molded into a sheet or film is impaired. Not preferred. A more preferred range is 1.2 million to
More preferably, it is 5,000,000, especially 1.5 to 3,000,000. The polypropylene used in the present invention must have a p-xylene soluble content at room temperature of 5 to 30% by weight. If the p-xylene solubles at room temperature is less than 5% by weight, it is not preferable because the soft polypropylene obtained by melt-kneading with an organic peroxide has poor transparency and impact resistance.
On the other hand, if the content exceeds 30% by weight, the flowability of the polymerized powder obtained by polymerization in the process of producing polypropylene is remarkably reduced, and it becomes difficult to melt-knead with the organic peroxide. In order to improve the transparency, impact resistance and fluidity of the polymerized powder of the obtained soft polypropylene, the p-xylene soluble matter at room temperature should be 7 to 25 wt%.
It is preferable that The polypropylene used in the present invention has a high weight average molecular weight, so that despite the relatively high p-xylene solubles at room temperature, the bulk specific gravity of the polymerized powder is high, and it is generally 0.30-0. .50 g / cc, and 0.5 g / cc
35 g / cc to 0.50 g / cc. The method for producing the polypropylene used in the present invention is not particularly limited, but for example, it can be produced by the following method. The following components [A], [B], [C] and [D] [A] Titanium compound [B] General formula R ¹ _n AlX _3-n (where R ¹ has 1 to ¹ carbon atoms)
An organoaluminum compound [C] represented by the formula: R ² _{n / 2} Al (OR ³ ) _{3-n / 2} (wherein X is a halogen atom, n is an integer of 1 to ³ )
R ² and R ³ are different or the same type of a saturated hydrocarbon having 1 to 10 carbon atoms, and n is an integer of 1 to 4). Polymerized, weight average molecular weight 100
It is a method to be more than ten thousand. As the titanium compound [A], a titanium compound known to be used for the polymerization of olefin is employed without any limitation. As a method for producing this catalyst, a known method is employed without any limitation. For example, JP-A-56-15520
No. 6, JP-A-56-136806 and JP-A-57-3410.
3, 58-8706, 58-83006, 58-
138708, 58-183709, 59-206
408, 59-219311, 60-81208,
60-81209, 60-186508, 60-
192708, 61-21309, 61-271
304, 62-15209, 62-11706, 62-72702, 62-104810, and the like. Specifically, for example, a method of co-milling titanium tetrachloride with a magnesium compound such as magnesium chloride, a titanium halide and a magnesium compound in the presence of an electron donor compound such as alcohol, ether, ester, ketone or aldehyde. Or a method in which a titanium halide, a magnesium compound and an electron donor compound are brought into contact in a solvent. As the titanium compound, known α, β, γ or δ-titanium trichloride is preferably used in addition to the above-mentioned supported catalyst. Methods for preparing these titanium compounds are described, for example, in JP-A-47-34478 and JP-A-50-1265.
90, 50-114394, 50-96888, 50-123091, 50-74594, 50-1
04191, 50-98489, 51-13662
5, 52-30888, and 52-35283. Next, as the organoaluminum compound [B], a compound known to be used for polymerization of an olefin is employed without any limitation. For example, trimethyl aluminum, triethyl aluminum, tri-n propyl aluminum, tri-n butyl aluminum, tri-i butyl aluminum, tri-n hexyl aluminum, tri-
Trialkylaluminums such as n-octylaluminum and tri-ndecylaluminum; diethylaluminum monohalides such as diethylaluminum monochloride and diethylaluminum bromide; alkylaluminum halides such as methylaluminum sesquichloride, ethylaluminum sesquichloride and ethylaluminum dichloride And the like. As the organic alkoxyaluminum compound [C], a compound known to be used for the polymerization of olefins is employed without any limitation. For example, dimethyl aluminum methoxide, dimethyl aluminum ethoxide, dimethyl aluminum isopropoxide, diethyl aluminum methoxide, diethyl aluminum ethoxide, diethyl aluminum n-butoxide, methyl aluminum sesquimethoxide, methyl aluminum sesqui ethoxide, ethyl aluminum sesqui ethoxide ,
Examples include ethylaluminum diethoxide, diisobutylaluminum ethoxide, ethylaluminum chloride monoethoxide and the like. Further, as the electron donor compound [D], a compound known to be used for improving the stereoregularity of an olefin is employed without any limitation. For example, methanol,
Alcohols such as ethanol, propanol, butanol, pentanol, hexanol, octanol, isopropyl alcohol, and isoamyl alcohol; phenols such as phenol, cresol, cumylphenol, xylenol, and naphthol; ketones such as acetone, methyl ethyl ketone, acetophenone, and benzophenone Acetaldehyde, propionaldehyde,
Aldehydes such as benzaldehyde; methyl formate, methyl acetate, ethyl acetate, vinyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, ethyl valerate, ethyl stearate, ethyl acrylate,
Organic acid esters such as methyl methacrylate, ethyl benzoate, methyl toluate, methyl anisate, ethyl phthalate, methyl carbonate, butyrolactone; ethyl silicate,
Silicates such as phenyltriethoxysilane;
Ethers such as methyl ether, ethyl ether, isopropyl ether, isoamyl ether, tetrahydrofuran, anisole, and diethylene glycol dimethyl ether; oxygen-containing electron donors such as amides such as acetic acid amide, benzoic acid amide, and maleic acid amide; methylamine, ethylamine Amines such as pyridine, piperidine, pyridine and aniline; nitriles such as acetonitrile and benzonitrile; nitrogen-containing electron donors such as isocyanate; sulfur-containing electron donors; In the present invention, prior to the main polymerization in the presence of each of the above-mentioned components, the prepolymerization of propylene in the presence of the same component can make the particle properties of the obtained polymerized powder highly fluid. It is suitable because it can be. In the prepolymerization, [A] and [B], and if necessary, [C] and / or [D]
Can be used. Since the amounts used in the prepolymerization of these components vary depending on the type of the catalyst and the polymerization conditions, the optimum amounts used may be determined in advance according to these conditions. An example of a generally preferred range is as follows. That is, the use ratio of the organoaluminum compound [B] is 0.1 to 100, preferably 0.1 to 20 in terms of Al / Ti (molar ratio) with respect to the titanium compound [A]. The organic alkoxyaluminum compound [C] used in accordance with
[C] / Ti (molar ratio) is in the range of 0.01-100, preferably 0.1-10, and the ratio of the electron donor [D] to the titanium compound [A] is [D]. / Ti (molar ratio): 0.01 to 100, preferably 0.01 to 10
Are each suitable. The amount of pre-polymerization of propylene in the presence of the catalyst component varies depending on the pre-polymerization conditions and the like.
Generally, it is sufficient to select from the range of 0.1 to 500 g / g · Ti compound, preferably 1 to 100 g / g · Ti compound. The propylene used in the prepolymerization is preferably used in terms of controlling the particle properties of the polymerized powder obtained by using a monomer of propylene alone, but within a range that does not adversely affect the physical properties of the polymerized powder, for example, 5 mol% The following other α-olefins, for example ethylene, 1-butene,
1-pentene, 1-hexene, 4-methylpentene-1
And the like are acceptable. It is also possible to make hydrogen coexist at each prepolymerization stage. In the prepolymerization, slurry polymerization is generally preferably applied. As a solvent, a saturated aliphatic hydrocarbon or an aromatic hydrocarbon such as hexane, heptane, cycloxane, benzene or toluene is used alone, or a mixed solvent thereof. Can be used. The prepolymerization temperature is preferably from -20 to 100 ° C, particularly preferably from 0 to 60 ° C. The pre-polymerization time may be appropriately determined according to the pre-polymerization temperature and the amount of polymerization in the pre-polymerization, and the pressure in the pre-polymerization is not limited, but in the case of slurry polymerization, generally, the pressure is from atmospheric pressure to 5 kg / c.
It is about m ² G. The prepolymerization may be performed in any of batch, semi-batch, and continuous methods. The main polymerization is carried out after the preliminary polymerization. Organoaluminum compound [B] used in the main polymerization
Is used in an amount of Al / Ti (molar ratio) based on titanium atoms.
Is preferably 1 to 1000 and 2 to 500. The amount of the organic alkoxyaluminum compound [C] used in the main polymerization is 0.01 to 10 mol, and preferably 0.1 to 10 mol, per 1 mol of the organic aluminum compound [B].
1 to 1.0 mole is preferred. Further, the amount of the electron donor compound [D] is preferably 0.001 to 10 mol, more preferably 0.01 to 1 mol, per 1 mol of the organic aluminum compound [B]. The order of addition of the above [B], [C], and [D] to the polymerization system is not particularly limited, and those in which the respective components are mixed in advance may be used. In the present polymerization in the present invention, propylene polymerization is carried out. The polymerization of propylene is based on propylene and 5
It may be carried out by feeding up to mol% of an acceptable mixture of α-olefins. When the polymerization conditions of the propylene are exemplified, the polymerization temperature is preferably as low as possible in order to increase the bulk specific gravity of the polymerization powder.
It is preferable to adopt 0 ° C. or lower, and more preferably from 20 to 70 ° C. If necessary, hydrogen can also be allowed to coexist as a molecular weight regulator. Furthermore, the polymerization may be any method such as slurry polymerization, gas phase polymerization, and solution polymerization using propylene itself as a solvent. Considering the simplicity of the process, the reaction rate, and the particle properties of the resulting polymerization powder, slurry polymerization using propylene itself as a solvent is the most preferred embodiment. Any of a polymerization system, a batch system, a semi-batch system, and a continuous system may be used, and the polymerization may be performed in two or more stages under different conditions. By the above main polymerization, a polymerization powder can be obtained. In the present invention, a method is preferred in which the polymer powder obtained by the above main polymerization is directly melt-kneaded in the presence of an organic peroxide. In performing the solvent mixing practice, the polymer and the organic peroxide are mixed, but the mixing method is not particularly limited. For example, a method of mechanically mixing using a blender such as a blender or a mixer, a method of dissolving an organic peroxide in an appropriate solvent and attaching the solution to a copolymer, and a method of mixing by drying the solvent. is there. As the melt-kneading temperature, a temperature not lower than the melting temperature of polypropylene and not lower than the decomposition temperature of organic peroxide is employed. However, if the heating temperature is too high, the polymer is thermally degraded. Generally, the melting temperature is 170-300 ° C,
In particular, it is preferable to set the temperature in the range of 180 to 250 ° C. Known organic peroxides are generally used for the present invention. Typical organic peroxides include:
Peroxides such as methyl ethyl peroxide and methyl isobutyl peroxide; diacyl peroxides such as isobutyryl peroxide and acetyl peroxide; diisopropylbenzene hydroperoxide; other hydroperoxides; 2,5-dimethyl-2,5- Di- (t-butylperoxy) hexane,
1,3-bis- (t-butylperoxyisopropyl)
1,1-di-dialkyl peroxide such as benzene;
t-butylperoxy-cyclohexane and other peroxyketals; t-butylperoxyacetate, t
Alkyl peresters such as -butylperoxybenzoate; t-butylperoxyisopropyl carbonate, and other percarbonates. The amount of the organic peroxide used is 0.001 to 1.0 part by weight, preferably 100 to 100 parts by weight of the raw material polypropylene, although it is not determined unconditionally depending on the set value of the melt index of the obtained soft polypropylene. Is 0.0
1 to 0.5 parts by weight is common. The weight-average molecular weight of the flexible polypropylene produced in the present invention is generally 100,000 to 700,000, preferably 150,000 to 600,000, in consideration of processability and stickiness. If the above range of the weight average molecular weight is represented by a melt flow rate, it is approximately 0.3 to 100 g / min.
Range. The molecular weight distribution of the flexible polypropylene produced in the present invention is 4.0 or less in the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography. It is preferably, and in consideration of transparency, it is more preferably 3.5 or less. The p-xylene soluble matter at room temperature of the soft polypropylene produced in the present invention is 10 to 40 wt.
%, More preferably 15 to 30 wt%. Further, the soft polypropylene produced in the present invention has a weight average molecular weight (M
w ¹ ) and the weight average molecular weight (M
w ²⁾ the ratio (Mw ¹ / Mw ²⁾ of it is more preferably preferably from 0.35 to 1.0 is at least 0.30. Further, the sheet has a value of Mw ¹ of 30,000 or more, preferably 50,000 or more, and more preferably 100,000 or more.
This is a more preferable embodiment in terms of stickiness when formed into a film or the like. The melting point of the soft polypropylene produced in the present invention is preferably in the range of 155 to 165 ° C. Various additives may be added to the soft polypropylene obtained in the present invention as long as the effects of the present invention are not impaired.
For example, antioxidants, heat stabilizers, light stabilizers, lubricants, antiblocking agents, nucleating agents, antistatic agents and the like can be added. The soft polypropylene obtained by the method of the present invention is excellent in processability, transparency, impact resistance, heat resistance and stickiness, and thus is suitable for various sheets, films, industrial parts and the like. Can be used. The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. The measuring method used in the following examples will be described. 1) Weight average molecular weight P. It was measured by C (gel permeation chromatography) method. Waters GPC-15
135 ° C. using o-dichlorobenzene as a solvent at 0 ° C.
I went in. The column used was Tosoh TSK-gel G
MH6-HT, gel size 10-15μ. The calibration curve used as a standard sample had a weight average molecular weight of 950, 290.
It was prepared using 0, 10,000, 50,000, 4.98 million, 2.7 million, and 4.9 million polystyrenes. 2) About 1.0 g of a polymer soluble in p-xylene at room temperature was added to 100 cc of p-xylene,
The temperature was raised to 130 ° C. with stirring, and stirring was further continued for 30 minutes to completely dissolve and prepare a uniform solution. Then, after allowing to cool to room temperature (23 ° C.), it was left at room temperature (23 ° C.) for 24 hours. The precipitated gel was filtered off, and the p-xylene solution was completely concentrated to determine the soluble content. [0038] It is represented by 3) Bulk specific gravity This was carried out in accordance with JIS K6712 (1977). 4) A test piece having a thickness of 1 mm was prepared by transparency injection molding, and JIS K
Performed according to 6714. 5) Izod impact was performed according to ASTM D-256. 6) Flexural modulus The test was performed in accordance with ASTM D-790. 7) Melting point A sample was prepared using a DSC-200 manufactured by Seiko Denshi Kogyo.
Hold at 0 ° C. for 10 minutes, cool to 120 ° C., perform isothermal crystallization at the same temperature for 10 minutes, cool to 50 ° C.,
The temperature was measured at 0 ° C./min. 8) Evaluation of stickiness A sheet having a thickness of about 0.3 mm was formed by a 30 mmφ sheet forming machine, and 10 sheets cut to 3.0 cm × 3.0 cm were piled up and left for 1 week under a load of 1 kg. The peeled state after the removal was determined based on the following criteria. A: There is no adhesion between the sheets, and all the sheets are excellent in peeling. B: There are adhesions on a few sheets, but they are peeled off relatively easily. C: Adhesion was found on 7 or more sheets, and peeling was relatively difficult. D: Adhesion of each sheet is remarkable, and it cannot be peeled at all. Example 1 (Preliminary polymerization) A 1-liter glass autoclave reactor equipped with a stirrer was sufficiently replaced with nitrogen gas, and 400 ml of heptane was charged. Reactor temperature 2
Keeping at 0 ° C., 0.18 mmol of diethylene glycol dimethyl ether, 22.7 mmol of ethyl iodide, 18.5 mmol of diethylaluminum chloride, and titanium trichloride (“TOS-1” manufactured by Marubeni Solvay Chemical Co., Ltd.)
7 ") After adding 22.7 mmol, propylene was continuously introduced into the reactor for 30 minutes so as to be 3 g per 1 g of titanium trichloride. The temperature during this period was kept at 20 ° C. After stopping the supply of propylene, the inside of the reactor was sufficiently replaced with nitrogen gas, and the obtained titanium-containing polypropylene was washed four times with purified heptane. As a result of the analysis, 2.9 g of propylene was polymerized per 1 g of titanium trichloride. [0050] (Polymerization) N _{2-substituted} 2 liters of 1 liter of liquid propylene the autoclave was subjected, diethylaluminum chloride 0.70 mmol, ethylaluminum sesquichloride ethoxide (Et1.5Al (oE
t) 1.5) 0.70 mmol and 0.007 mmol of methyl methacrylate were added, and the internal temperature of the autoflag was reduced to 7
The temperature was raised to 0 ° C. 0.087 mmol of titanium-containing polypropylene was used as titanium trichloride, and propylene was polymerized at 70 ° C. for 3 hours. No hydrogen was used during this time. Unreacted monomers were purged to obtain 77 g of a granular polymerization powder. The obtained polymerization powder was brought into contact with a propylene oxide-H ₂ O mixed solution and dried at 70 ° C. for 1 hour. Next, an antioxidant, a heat stabilizer, and a chlorine scavenger are added and mixed, and then, as an organic oxide, 1,3
-Bis- (t-butylperoxyisopropyl) -benzene was added at 0.10 wt%, and extruded at 250 ° C using a 20 mmφ extruder to obtain pellets. The results are shown in Table 1. Example 2 The procedure of Example 1 was repeated, except that the amount of ethyl aluminum sesquiethoxide was changed to 0.21 mmol in the polymerization of Example 1. The results are shown in Table 1. Examples 3 and 4 The same operation as in Example 1 was carried out except that the amount of methyl methacrylate added in the polymerization of Example 1 was changed to 0.0035 mmol and 0.014 mmol. The results are shown in Table 1. Examples 5 and 6 The amount of the organic peroxide added in Example 1 was 0.05 wt%,
The same operation as in Example 1 was performed except that the content was 0.30% by weight. The results are shown in Table 1. Comparative Example 1 The same operation as in Example 1 was carried out except that the ethyl aluminum sesquiethoxide was not used in the polymerization of Example 1. The results are shown in Table 1. Comparative Example 2 The same operation as in Example 1 was carried out except that the amount of methyl methacrylate added was changed to 0.07 mmol in the polymerization of Example 1. The results are shown in Table 1. Comparative Example 3 In the polymerization of Example 1, the concentration of H ₂ in the gas phase was 2.0
mol% and introduced into an autoclave for polymerization. The same operation as in Example 1 was performed except that no organic peroxide was used. The results are shown in Table 1. Comparative Example 4 A polymerization was carried out in the same manner as in Example 1 except that methyl methacrylate was not added. The resulting polymer powder had remarkable mutual adhesion between particles, and it was impossible to granulate in the presence of an organic peroxide. The results are shown in Table 1. Comparative Example 5 In the polymerization of Example 1, H ₂ was added at a concentration in the gas phase of 0.4.
The same operation as in Example 1 was performed except that the mol% was introduced into the autoclave. The results are shown in Table 1. Example 7 In the polymerization of Example 1, H ₂ was added at a concentration in the gaseous phase of 0.0
The same operation as in Example 1 was performed except that the content was introduced into the autoclave so as to be 2 mol%. The results are shown in Table 1. Example 8 In the polymerization of Example 1, diethylene glycol dimethyl ether was used in place of methyl methacrylate in the amount of 0.00
The same operation as in Example 1 was performed except that the amount was changed to 35 mmol. The results are shown in Table 1. [Table 1]

Claims (1)

(57) [Claims] [Claim 1] The weight average molecular weight is 1,000,000 or more,
A method for producing a soft polypropylene, comprising melt-kneading polypropylene having a xylene-soluble content of 5 to 30 wt% in the presence of an organic peroxide.