JPS623864B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyolefin compositions. More specifically, the present invention relates to a polyolefin composition which is a mixture of a high molecular weight polyolefin and a low molecular weight polyolefin and has excellent impact resistance, environmental cracking resistance and moldability. The higher the average molecular weight of so-called high-density polyethylene, which has a density of 0.940 or higher, the higher the performance of the plastic.Of these, impact resistance and environmental cracking resistance are particularly improved in the high molecular weight range, especially in the melt index of less than 0.05. do. On the other hand, plastics such as high-density polyethylene are generally commercialized by melt molding, but when the average molecular weight is increased to provide the above-mentioned characteristics, the flow during melting becomes poor and so-called moldability decreases. When the melt index was less than 0.05, it was necessary to take measures to maintain moldability. One of the ways to obtain high-density polyethylene with impact resistance, environmental crack resistance, and formability is to
Japanese Patent Publication Nos. 40-5208 and 45-3215 propose compositions containing high molecular weight polyethylene and low molecular weight polyethylene. However, in these compositions, the melt index of the resulting polyolefin composition is 0.05.
This is just the goal being achieved. The present inventors investigated the impact resistance, environmental cracking resistance, and moldability of polyolefin compositions with a melt index of less than 0.5, and found that when the melt index was less than 0.05,
In addition to specifying the density, molecular weight, blending ratio, etc. of the polyethylene to be mixed, by specifying the catalyst for producing polyethylene, we have determined that it has excellent impact resistance, environmental cracking resistance, and particularly excellent formability. The present invention has been accomplished by discovering that a polyolefin composition can be obtained. That is, the gist of the present invention is that the density is 0.915~
0.955, 30 to 70 parts by weight of polyolefin A with a viscosity average molecular weight of 300,000 to 700,000, and polyolefin B70 to 30 with a density of 0.940 to 0.977 and a viscosity average molecular weight of 10,000 to 40,000.
Polyolefin A and polyolefin B are a reaction product of an oxygen-containing organic compound of magnesium and a titanium halogen compound, or a reaction product of an oxygen-containing organic compound of magnesium, an oxygen-containing organic compound of titanium, and an aluminum halogen compound. using an ethylene homopolymer or a copolymer of ethylene and other α-olefin produced using a catalyst consisting of a reaction product of The polyolefin composition consists of a polyolefin B having a viscosity average molecular weight of 15 to 55 and a melt index of less than 0.05. To explain the present invention in detail, polyolefin A and polyolefin B mixed in the present invention are ethylene homopolymer or ethylene and other α
- It is a copolymer with olefin. Examples of other α-olefins in the copolymer include propylene and butene-1, and those whose content is 10% by weight or less, preferably 5% by weight or less are usually used. Its physical properties are selected as follows. First, polyolefin A has a density of
Those with a viscosity average molecular weight of 0.915 to 0.955 and a viscosity average molecular weight of 300,000 to 700,000 are used. where density is ASTM D1505
The viscosity average molecular weight is 130.
Measure the intrinsic viscosity in the tetralin solution at °C,
[η] = 4.60×10 ^-4 × M ⁰ . ⁷²⁵ ([η] is the limiting viscosity,
M is a value calculated from the formula (viscosity average molecular weight). However, if the density is lower than this range, the stiffness of the composition will be too low, and if the viscosity average molecular weight is less than 300,000, the impact strength, tear strength, and environmental cracking resistance of the polyolefin composition will be low; If it exceeds this value, moldability will decrease, which is not preferable. The weight average molecular weight/number average molecular weight (measured by gel permeation chromatography) is 4 to 8, and the melt index (according to the measurement method described later) is 0.012.
~0.0004 is preferred. On the other hand, polyolefin B has a density of 0.940.
~0.977, and a viscosity average molecular weight of 10,000 to 40,000, preferably 10,000 to 35,000. If the density is lower than this range, the stiffness of the composition will be insufficient, if the viscosity average molecular weight is less than 10,000, the impact strength of the polyolefin composition will decrease, and if it exceeds 40,000, the moldability will decrease. Undesirable. The weight average molecular weight/number average molecular weight is preferably 4 to 8, and the melt index is preferably 24 to 1,300. Furthermore, in the present invention, (viscosity average molecular weight of polyolefin A)/(viscosity average molecular weight of polyolefin B) is 15 to 55, preferably 20 to 50. If this ratio is less than 15, the moldability of the polyolefin composition decreases, and if it exceeds 55, the impact strength of the polyolefin composition decreases, which is not preferable. Therefore, polyolefin A and polyolefin B used in the present invention are the reaction products (a) of an oxygen-containing organic compound of magnesium and a titanium halide compound, or a reaction product (a) of an oxygen-containing organic compound of magnesium, an oxygen-containing organic compound of titanium, and aluminum. It is produced using a catalyst consisting of a reaction product (b) with a halogen compound and an organoaluminum compound. By using polyolefins produced using these catalysts, polyolefin compositions with particularly excellent moldability can be obtained, and other catalysts such as titanium trichloride-alkylaluminium, titanium tetrachloride-trialkoxyvanadyl-based This is advantageous over using polyfins made with aluminum alkyl systems. To explain the catalyst used, the oxygen-containing organic compound of magnesium used when preparing the reaction product (a) is Mg(OR ¹ ) _n X ¹ _2-n
(In the formula, R ¹ represents an alkyl group, aryl group or cycloalkyl group, X ¹ represents a halogen atom,
m represents 1 or 2. ) Examples include magnesium diethoxide, magnesium dimethoxide, magnesium diphenoxide, magnesium monoethoxy chloride, magnesium monophenoxy chloride, magnesium monoethoxy bromide, magnesium monoethoxy iodide, and the like. The titanium halogen compound has the general formula TiX ² _o (OR ² ) _4-o (wherein, X ² represents a halogen atom, R ² represents an alkyl group, an aryl group, or a cycloalkyl group, and n represents 1 to 4 ), such as titanium tetrachloride,
Examples include titanium tetrahalides such as titanium tetrabromide and titanium tetraiodide, titanium monoethoxytrichloride, titanium monomethoxytribromo, and titanium diethoxydichloride. Among these, titanium tetrahalide is preferred. The reaction between the oxygen-containing organic compound of magnesium and the titanium halide compound is carried out at 50°C or higher in the presence or absence of an inert hydrocarbon solvent.
It is carried out by contact at a temperature of 200°C. The reaction product is obtained as a precipitate, and the unreacted product is removed by washing with an inert hydrocarbon solvent.There is no particular limit to the atomic ratio of titanium to magnesium, but if it is too large, titanium will be wasted. , the polymerization activity decreases. So usually
It is preferable that the molar ratio of Ti/Mg is 0.1 to 100. Next, the oxygen-containing organic compound of magnesium used in preparing the reaction product (b) is:
Magnesium compounds of the general formula shown above may likewise be mentioned. ^The oxygen-containing organic compound ^of titanium has the general formula _Ti ^{(OR 3 )} _k (representing a number from 1 to 4), for example, tetraethoxytitanium,
Examples include tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetraphenoxy titanium, triethoxy monochloro titanium, tri-n-butoxy monochloro titanium, diethoxy dichloro titanium, tri-n-butoxy monobrom titanium, and the like. Among these, compounds with k of 3 or 4 are preferred. _The ^aluminum halogen ^compound has ^the general formula AlR ⁴ _p ), such as ethylaluminum dichloride, normal propylaluminum dichloride, ethylaluminum sesquichloride, diethylaluminum monochloride, and the like. Among these, compounds in which X ⁴ is chlorine and p is 1 are preferred. The reaction between the oxygen-containing organic compound of magnesium, the oxygen-containing organic compound of titanium, and the aluminum halide is carried out by first mixing the oxygen-containing organic compound of magnesium and the oxygen-containing organic compound of titanium and heating the mixture to 100°C to 160°C. Prepare a homogeneous liquid. If it is difficult to produce a uniform liquid, it is preferable to include alcohol.
Next, an inert hydrocarbon solvent is added to obtain an inert hydrocarbon solution. When alcohol is used, it is preferable to remove the alcohol by distillation or the like. When an aluminum halogen compound is added to the inert hydrocarbon solution obtained as described above and reacted at room temperature to 100°C, the reaction product is obtained as a precipitate, and the unreacted material is evaporated with an inert hydrocarbon solvent. It is purified. The quantitative ratio of each component is the atomic ratio of titanium to magnesium (Ti/Mg) of 0.1.
~10, the ratio of the sum of gram equivalents of all halogens to the sum of gram equivalents of magnesium and titanium (X/Mg+Ti), preferably 1.0 to 20. Note that the total halogen herein refers to the halogen contained in the oxygen-containing organic compound of magnesium, the oxygen-containing organic compound of titanium, and the aluminum halogen compound. On the other hand, ^the organoaluminum compound used as a cocatalyst has the general formula AlR ⁵ _q X ⁵ _3-q (wherein R ⁵ represents an alkyl group, aryl group or cycloalkyl group, represents a number from 1 to 3), such as triethylaluminum, tri-n-propyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, diethylaluminum monochloride, di-n-propyl aluminum monochloride, and the like. Ethylene homopolymers or copolymers of ethylene and other α-olefins can be produced by combining ethylene or ethylene with the reaction product (a) or (b) obtained as described above and an organic aminium compound. Other α−
It is produced by polymerizing a mixture with olefin. Polymerization may be carried out by a conventional method, at a temperature of room temperature to 200°C in the presence or absence of an inert hydrocarbon solvent,
It is carried out at a pressure of normal pressure to 100 atmospheres in the presence of hydrogen or the like. The ratio of the reaction product (a) or (b) to the organoaluminum compound is usually selected from the range of 0.05 to 100, preferably 0.07 to 50 in terms of Al/Ti atomic ratio. However, polyolefin A and polyolefin B
The mixing ratio is 30 parts by weight to 70 parts by weight of polyolefin A per 100 parts by weight of the composition.
B70 to 30 parts by weight. Polyolefin A
is less than 30 parts by weight and polyolefin B exceeds 70 parts by weight, the impact strength, tear strength, and environmental cracking resistance of the polyolefin composition decreases; This is not preferable because the moldability of the polyolefin composition decreases. The mixing method is not particularly limited and any known method may be used. For example, a solution mixing method CIM (Continuos Intensive Mixer) in which polyolefins A and B are dissolved individually or together in a solvent, mixed, and then precipitated;
Examples include a continuous melt-kneading method using an FCM (Farrl Continuos Mixer) or a single-screw extruder, and a batch-type melt-kneading method using a Banbury mixer or the like.
Among these, mixing using a Banbury mixer is preferred in terms of uniformity of the blended polymer. However, in the present invention, polyolefin A and polyolefin B are mixed and the melt index is 0.05.
The polyolefin composition shall be less than or equal to Here, the melt index is based on ASTMD-1238, 190
℃, value measured under 2.16 kg load, unit is g/10
It's a minute. When it is 0.05 or more, the impact strength, tear strength, and environmental cracking resistance of the polyolefin composition are significantly reduced, making it impractical for thin films and the like. As described above, the composition of the present invention has excellent impact strength, tear strength, environmental cracking resistance, and particularly moldability. The resin is suitable for extrusion molding or blow molding. That is, the composition of the present invention has a large amount of extrusion per rotational speed in an extruder and high productivity in extrusion molding, and is therefore suitable for extrusion molding.
In particular, when formed into an extremely thin film, its tear strength is high. Further, when a large-sized blow container is formed by blow molding, the high tensile impact strength and environmental cracking resistance are particularly advantageous. Next, the present invention will be explained in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In the following examples, the amount of extrusion molding as a measure of moldability was determined using a Brabender 21D single-screw extruder (diameter 19.1 mmφ, L/D = 21, compression ratio = 3).
The extrusion amount was measured at a die temperature of 200℃ and a rotation speed of 150 rpm using a full-flight screw with a diameter of 20 mm and a circular die with a clearance of 0.5 mm.
The extrusion amount was divided by the number of revolutions (150 revolutions/min) to determine the amount of extrusion molded per number of revolutions. Environmental crack resistance is
It was measured by the Bell telephone method described in ASTMD-1693. The time required for 5 out of 10 test pieces to break was expressed. Tensile impact strength was determined by ASTMD-1822L. The tear strength as the strength of the formed film was measured using a notched Elmendorf ASTMD-1922.The film was manufactured by the inflation film method under the following conditions. Extruder: 40mmφ diameter, manufactured by Modern Machinery Extruder screw: Full flight screw,
L/D = 24, compression ratio 3.5 Molding die: 50mmφ circular die, clearance 0.7mm Temperature: C ₁ = 180℃, C ₂ = 190℃, C ₃ = 200℃, die head = 210℃, die = 210℃ Extrusion rate: 7Kg/hr Frost line: 25cm Blow-up ratio: 3 Film thickness: 25μ The viscosity average molecular weight was measured according to the method described above.
Melt index (abbreviated as MI) is ASTMD-
Measured at 190℃ and under a load of 2.16Kg based on 1238. The flow rate ratio (abbreviated as FR) is the shear stress value measured in a melt indexing device based on ASTM-1238.
It was determined by the ratio of the outflow amount at 10 ⁶ dyne/cm ² and 10 ⁵ dyne/cm ² . Density was measured according to ASTM D-1505. The weight average molecular weight/number average molecular weight (abbreviated as M _W /M _N ) was determined by measuring the molecular weight distribution by gel permeation chromatography under the following conditions and calculating from the distribution. In addition, the molecular weight distribution was determined by calculating a calibration curve from the chromatography count number to the viscosity average molecular weight of the fractionated polyethylene, and then using this calibration curve to determine the distribution. Model: Waters Model 200 Chromatography Solvent: O-dichlorobenzene Column: Polystyrene gel GMS (Toyo Soda Co., Ltd., trademark) 4-way flow rate: 1 c.c./min Polyethylene concentration: 0.25% by weight Charge amount :2c.c. Reference example Polymerization was carried out using any of the following catalyst systems A, B, C, or D at an ethylene partial pressure of 5.0 Kg/cm ² , a hydrogen partial pressure shown in Table 1, and a temperature of 90°C. , polyethylene having the physical properties shown in Table 1 was produced. (a) 10.0 g of Mg (OC ₂ H ₅ ) ₂ and 70 ml of TiCl ₄ at 130℃
- Reacted for 2 hours. After cooling, it was washed with n-hexane and the supernatant liquid was removed. After repeating this several times, a catalyst consisting of the obtained solid and triisobutylaluminum is obtained. (b) Mg (OC ₂ H ₅ ) ₂ 100 mmol and Ti (OC ₄ H ₉ ) ₄ 100 m
mol and were mixed at 150°C for 3 hours to homogenize.
After cooling, 500 ml of n-hexane was added, and while stirring thoroughly, 600 mmol of AlC ₂ H ₅ Cl ₂ was gradually added dropwise.
A solid precipitate begins to form from the beginning of dripping, but
After the completion of the dropwise addition, this slurry was aged at 65°C for 2 hours, and further washed with n-hexane to remove the supernatant liquid. A catalyst consisting of a solid obtained by repeated washing with n-hexane and toirisobutylaluminum. (c) Commercially available titanium trichloride (manufactured by Toyo Stouffer Co., Ltd.)
A catalyst consisting of AA titanium trichloride) and triisobutylaluminum. (d) An equimolar mixture of titanium tetrachloride and tri-n-butoxyvanadyl VO(OC ₄ H ₉ ) ₃ was treated in cyclohexane at 60°C, and then ethylaluminum sesquichloride was added at 25°C to reduce the resulting solid. A catalyst consisting of triisobutylaluminum.

【table】

[Table] Examples 1 to 7 and Comparative Examples 1 to 10 Using the polyolefin produced in the reference example, high molecular weight components (components A1 to 13) and low molecular weight components (components
B1 to B11) were mixed using a Banbury mixer or using a solution in the proportions shown in Table 2. Table 2 shows the results of measuring the physical properties of the obtained polyolefin composition. The details of the mixing method are as follows. Mixing using a Banbury mixer: Polyolefin powders A and B are mixed at a predetermined weight ratio, and the total amount of polyolefin powders A and B is 260 g. This mixed powder is charged into a Banbury mixer, and the mixer is sufficiently purged with nitrogen. Knead for 3 minutes at a rotation speed of 200 rpm and a shear rate of 420 sec ^-1 . Mixing by solution: Polyolefins A and B are added in a predetermined weight ratio to a total amount of 300 g into a 50-pressure stirring bed. Charge 3.5 liters of toluene as a solvent. The inside of the stirring tank is replaced with nitrogen, and the temperature is raised to 180°C while stirring. Stir at 180°C for 42 hours to blend the polymer.
After cooling to below the boiling point, it is precipitated into methanol 20 to obtain a polymer.

【table】

Claims (1)

[Claims] 1. Density 0.915 to 0.955, viscosity average molecular weight 300,000 to 70
10,000 polyolefin A30-70 parts by weight, density
0.940 to 0.977 and 70 to 30 parts by weight of polyolefin B having a viscosity average molecular weight of 10,000 to 40,000, as polyolefin A and polyolefin B.
General formula Mg(OR ¹ ) _n X ¹ _2-n (wherein, R ¹ represents an alkyl group, an aryl group or a cycloalkyl group,
X ¹ represents a halogen atom, m represents 1 or 2) and a magnesium oxygen-containing organic compound with the general formula TiX ² _o (OR ² ) _4-o (wherein, X ² represents a halogen atom, ^R2 represents an alkyl group, an aryl group, or a cycloalkyl group, and n represents a number from 1 to 4) or a reaction product of a magnesium halogen compound represented by the above general formula or an oxygen-containing organic compound of magnesium represented by the general formula shown above. and the general formula Ti
⁽ _OR ³ ₎ ^{k _} Oxygen-containing organic compounds and general formula of titanium
_Represented ^by _AlR ^{4 p _} The reaction product with an aluminum halogen compound and the general formula AlR ⁵ _q X ⁵ _3-q (wherein R ⁵ is an alkyl group,
an aryl group or a cycloalkyl group, X ⁵ is a halogen atom, and q is a number from 1 to 3). using a copolymer with α-olefin, and (viscosity average molecular weight of polyolefin A)/(viscosity average molecular weight of polyolefin B)
A polyolefin composition having a melt index of less than 0.05, having a melt index of 15 to 55. 2. The polyolefin composition according to claim 1, wherein polyolefin A and polyolefin B are mixed in a Banbury mixer. 3. The polyolefin composition according to claim 1 or 2, wherein polyolefin A and polyolefin B are mixed into a solution.