JPH10338717A - Propylene homopolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject homopolymer having a sufficient melt tension, melt viscoelastic properties and the like, and excellent in melt processability by securing specific relationships between melt index and molecular weight distribution, and between melt tension and intrinsic viscosity, and also by securing a specific intrinsic viscosity. SOLUTION: This homopolymer is obtained by securing the relationships of MI5 /MI2.16 >=0.24×Mw /Mn +3.1 (MI5 is melt index at 230 deg.C and load of 5.0 kg; MI2.16 is melt index at 230 deg.C and load of 2.16 kg; Mw is weight-average molecular weight; and Mn is number-average molecular weight), and logMS>=3.17×log[η]-0.68 (MS is melt tension at 230 deg.C and [η] is intrinsic viscosity at 135 deg.C in tetralin as the solvent, and also securing the intrinsic viscosity [η] in the range of 0.1 to 15.0 dl/g. This polymer can be controlled for its melt tension, and is suitable for, e.g. foaming, sheet forming and blow molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propylene homopolymer, and more particularly to a propylene homopolymer, which has properties equal to or higher than that of a conventional propylene polymer, has excellent melt processing characteristics, and is particularly suitable for large-size blow molding and extrusion. The present invention relates to a propylene homopolymer suitably used for foam molding and the like.

[0002]

2. Description of the Related Art Conventionally, polypropylene has (1) a high mechanical strength such as rigidity and an excellent balance of physical properties.
(2) It is chemically stable, has excellent weather resistance and is not easily immersed in chemicals, etc. (3) It has a high melting point and excellent heat resistance.
(4) It has features such as light weight and inexpensiveness, is excellent in melt moldability, and can be applied to melt molding methods such as extrusion molding, blow molding, injection molding, and inflation molding. Widely used. Polypropylene having such characteristics is actively used for automobile parts, etc., taking advantage of its excellent properties.However, further improvements in performance and cost reductions such as labor saving in the molding process are strongly demanded. ing. Therefore, if large parts conventionally manufactured by injection molding can be manufactured by blow molding, the manufacturing cost can be greatly reduced.

[0003] However, in the conventional polypropylene, the melt tension and the melt viscoelasticity are insufficient, and the stability of the parison in large blow molding is inferior. Was. Further, when the molecular weight is increased to improve the melt tension, the melt fluidity is reduced, and there is a problem that the method cannot be applied to molding of a complicated shape. In the field of foamed molded articles, demands for foamed articles having heat resistance as well as weight reduction, heat insulating properties, vibration damping properties, etc. are increasing, and foamed articles made of polypropylene are expected.
In fact, the melt tension of conventional polypropylene is insufficient, and it is difficult to obtain a sufficiently satisfactory foam molded article. In order to further expand the field of use of this polypropylene, it is necessary to improve the extrusion processability. Conventionally, various attempts have been made to improve the melt processability of polyolefins.For example, by improving the polymerization catalyst and polymerization recipe during the production of polyolefins and expanding the molecular weight distribution, the melt processability is improved. And a method of partially cross-linking a polyolefin to improve melt processability.

[0004] On the other hand, in the case of ethylene-based polymers, recently, despite the narrow molecular weight distribution due to the catalyst system combining a metallocene catalyst and aluminoxane, etc.
An ethylene polymer having an improved melt tension has been proposed (JP-A-4-213306). It is also disclosed that the ethylene-based polymer produced by the constrained geometry addition type catalyst has an improved melt tension despite its narrow molecular weight distribution (Japanese Patent Laid-Open No. 3-163).
088), suggesting the existence of long-chain branching. A mechanism has been proposed in which the generation of the long-chain branch is such that an ethylene-based polymer having a vinyl group at the molecular chain end is generated at the time of polymerization, and this is polymerized again as a macromonomer. By the way, as a method for improving the melt tension of polypropylene, a method of mixing (1) a high-molecular-weight high-density polyethylene with a high melt tension (Japanese Patent Publication No. 6-55)
868), (2) a method of mixing high-density polyethylene having a high melt tension produced by a chromium-based catalyst (Japanese Patent Application Laid-Open No. 8-92438), and (3) a general high-pressure radical polymerization method. A method of mixing low-density polyethylene, (4) a method of increasing melt tension by irradiating general polypropylene with light, and (5) a method of irradiating general polypropylene with light in the presence of a crosslinking agent or peroxide. (6) a method of grafting a radical polymerizable monomer such as styrene to general polypropylene, and (7) a method of copolymerizing propylene and a polyene (JP-A-5-194778, JP-A-5-194778). No. 194779) has been attempted.

However, in the above-mentioned methods (1) to (3), the elasticity, strength and heat resistance of the component for increasing the melt tension are insufficient, so that the inherent characteristics of polypropylene are inevitably lost. Further, in the methods (4) and (5), it is difficult to control a cross-linking reaction occurring as a side reaction. There is a limit in arbitrarily controlling, and there is a problem that a control range is narrow. Further, in the method (6), the chemical stability of the polypropylene is impaired, and in the case of the styrene-based graft, a problem occurs in the resin recyclability. In the method (7), the melt tension is reduced. The effect of improvement is small, sufficient effect is not exhibited, and generation of gel is also concerned.

[0006]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a material having the same or higher physical properties as the conventional propylene-based polymer and having sufficient melt tension, melt viscoelasticity, melt fluidity, etc. The present invention provides a propylene homopolymer having excellent melt processing properties and particularly suitably used for large-size blow molding, extrusion foam molding and the like.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to develop a propylene homopolymer having excellent melt processing properties. As a result, the melt index and the molecular weight distribution, the melt tension, and the intrinsic viscosity were each determined. It has been found that a propylene homopolymer having a specific relationship and a predetermined intrinsic viscosity can be suitable for the purpose. The present invention has been completed based on such findings. That is, the present invention relates to (a) a load of 5.0 kg measured at a temperature of 230 ° C.
Index MI ₅ (g / 10 min) and load 2.
Melt index MI _2.16 at 16 kg (g / 10
The ratio MI ₅ / MI _2.16 with min), the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn measured by gel permeation chromatography is of the formula MI ₅ / MI _2.16 ≧ 0.240 × Mw / Mn + 3.1 (I), and (b) the melt tension MS (g) measured at a temperature of 230 ° C. and the intrinsic viscosity [η] measured in a tetralin solvent at a temperature of 135 ° C. (Dl /
g) satisfies the relationship of logMS ≧ 3.17 × [η] −0.68 (II), and the intrinsic viscosity [η] is 0.1 to 15.0.
The present invention provides a propylene homopolymer characterized by being in the range of dl / g.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The propylene homopolymer of the present invention is produced from only a propylene monomer, has a narrow molecular weight distribution, can control the non-Newtonian property of melt flow, and can control the melt tension. Is a long-chain branched propylene homopolymer having an excellent balance of the following properties and has the following properties. First, the load measured at a temperature of 230 ° C. 5.
The melt index MI ₅ at 0 kg (g / 10 minutes) and the melt index MI _2.16 at a load of 2.16 kg (g /
The ratio MI ₅ / MI _2.16 with 10 min), the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn measured by gel permeation chromatography (GPC) method, wherein MI ₅ / MI _2.16 ≧ 0.240 × Mw / Mn + 3.1 (I) If MI ₅ / MI _2.16 is smaller than the value of “0.240 × Mw / Mn + 3.1”, the melt processability is poor, and the object of the present invention cannot be achieved.
From the viewpoint of melt processability, preferably, MI ₅ / MI _2.16 ≧ 0.240 × Mw / Mn + 3.8, more preferably MI ₅ / MI _2.16 ≧ 0.240 × Mw / Mn + 4.5.

The above Mw / Mn is a value calculated from the weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of polyethylene measured by the GPC method using the following apparatus and conditions. Apparatus: Main unit Waters ALC / GPC 150
C column Tosoh TSK MH + GMH 6 × 2 condition: temperature 135 ° C. solvent 1,2,4-trichlorobenzene flow rate 1.0 ml / min. Next, melt tension MS measured at 230 ° C.
(G) and an intrinsic viscosity [η] (dl / g) measured in a tetralin solvent at a temperature of 135 ° C. are represented by the following formula: logMS ≧ 3.17 × log [η] −0.68 (II) It is necessary to satisfy the relationship. logMS is "3.1
If the value is smaller than 7 × log [η] −0.68 ″,
Inferior in melt processability, and the object of the present invention cannot be achieved. From the viewpoint of melt processability, preferably logMS ≧ 3.17 × log [η] −0.57, more preferably logMS ≧ 3.17 × log [η] −0.46, particularly preferably logMS ≧ 3.17 × log [Η] −0.35.

The intrinsic viscosity [η] is 0.1 to 15.0.
It needs to be in the range of dl / g. This [η] is
If it is less than 0.1 dl / g, the melt processability is poor and the mechanical strength is insufficient. If it exceeds 15.0 dl / g, the melt viscosity is high and the melt processability is reduced. From the viewpoint of the balance between melt processability and mechanical strength, [η] is preferably from 0.4 to 10.0 dl / g, particularly preferably from 0.6 to 6.0 dl / g.
A range of dl / g is preferred. The melt tension MS is:
It is a value measured under the following conditions using Capillograph 1B manufactured by Toyo Seiki Co., Ltd. Capillary: diameter 2.095mm, length 8.0m
m Cylinder diameter: 9.6 mm Cylinder extrusion speed: 10 mm / min Winding speed: 3.14 m / min Temperature: 230 ° C

Further, the propylene homopolymer of the present invention preferably has a ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn in the range of 1.5 to 4.5.
If Mw / Mn exceeds 4.5, the molecular weight distribution is too wide,
It is difficult to obtain a material having sufficiently satisfactory physical properties. Also, M
When w / Mn is less than 1.5, it is practically difficult to produce. From the viewpoint of physical properties, a more preferable Mw / Mn is 1.
The range is from 5 to 4.0, and particularly preferably from 1.5 to 3.5. Further, the melting point Tm measured by a differential scanning calorimeter (DSC) is preferably in the range of 120 to 165 ° C. If the melting point is less than 120 ° C., the heat resistance is insufficient, while if it exceeds 165 ° C., the molding temperature becomes too high, which is not economically preferable. Considering the heat resistance and the economics of molding, the more preferable range of the melting point is 130 to 165 ° C. The melting point Tm is determined by using a differential scanning calorimeter “DSC-7” manufactured by Perkin-Elmer Co., Ltd. It is a value measured by the following method. That is, a sheet obtained by hot pressing at 190 ° C. is used as a sample, melted at 200 ° C. for 5 minutes by DSC-7, cooled down to 20 ° C. at a rate of 10 ° C./min, and held for 5 minutes. The temperature is raised at a rate of 10 ° C./min, and the melting point Tm is determined from the endothermic peak observed in this process.

Further, the propylene homopolymer of the present invention preferably has a low molecular weight component and a small amount of atactic portion. For example, the content of the component soluble in diethyl ether is preferably 2% by weight or less, particularly preferably 1% by weight or less. The content of the component soluble in diethyl ether is a value measured by the following method. That is, about 3 g of a powdery polymer was placed in a Soxhlet extractor and extracted with 160 ml of diethyl ether for 6 hours. Thereafter, the extraction solvent was distilled off with a rotary evaporator, and the components soluble in diethyl ether were recovered by vacuum drying, and the weight was measured. The method for producing the propylene homopolymer of the present invention is not particularly limited as long as it is a method capable of obtaining a propylene homopolymer satisfying the above requirements, and for example, reacting propylene in the presence of an olefin polymerization catalyst. By polymerizing propylene with the reactive macromonomer obtained by the above in the presence of an olefin polymerization catalyst, a desired propylene homopolymer can be efficiently produced. At this time, the catalyst for olefin polymerization is not particularly limited, and various catalysts can be used, but a metallocene composed of a transition metal compound shown below and a compound capable of reacting therewith to form an ionic complex is used. A system catalyst is preferably used.

Typical examples of the transition metal compound include two or more indenyl groups having substituents which are capable of controlling the steric structure of the polymer and which are bridged at the five-membered ring portion by one or two bridging groups. And transition metal compounds belonging to Group 4 of the periodic table having the above ligand. As transition metals of Group 4 of the periodic table, titanium, zirconium, and hafnium are preferred. As the transition metal compound of Group 4 of the periodic table having an indenyl skeleton, for example, (a) Hoechst, a BASF-type complex, and (b) a double-bridge type complex can be used. Examples of the Hoechst and BASF-type complexes of (a) include rac-dimethylsilylene-bis (2-methyl-4-phenylindenyl) zirconium dichloride and rac-dimethylsilylene-bis (2-methyl-5,6-benzoin). (Denyl) zirconium dichloride, rac-ethylenebisindenyl zirconium dichloride, and the like, and titanium and hafnium compounds corresponding to these zirconium compounds. on the other hand,
Examples of the double-crosslinked complex (b) include (1, 1)
2′-ethylene) (2,1′-ethylene) -bis (4
7-dimethylindenyl) zirconium dichloride,
Examples thereof include (1,2′-ethylene) (2,1′-ethylene) -bis (4-phenylindenyl) zirconium dichloride and titanium and hafnium compounds corresponding to these zirconium compounds.

On the other hand, examples of the compound capable of forming an ionic complex by reacting with the transition metal compound include an aluminum oxy compound, an ionic compound composed of a cation and an anion having a plurality of groups bonded to an element, and a Lewis acid. Among these, an aluminum oxy compound is preferable, and an aluminoxane is particularly preferable. Examples of the aluminoxane include methylaluminoxane, ethylaluminoxane, n-propylaluminoxane, isobutylaluminoxane, methyl-ethylaluminoxane, methyl-n-propylaluminoxane, methyl-isopropylaluminoxane, ethyl-n-propylaluminoxane, ethyl-isopropylaluminoxane and the like. And mixtures of two or more of these. As for the propylene macromonomer used in this method, it is preferable to continuously produce a macromonomer and a propylene homopolymer using a single reactor, but only the macromonomer is produced and added during the production of the propylene homopolymer. Alternatively, in a single-stage polymerization, a macromonomer and a propylene homopolymer can be simultaneously produced. At this time, the catalyst for producing the propylene homopolymer and the catalyst used for producing the macromonomer are preferably the same, but different catalysts can be used.

The polymerization method is not particularly limited, and any method such as a slurry polymerization method, a gas phase polymerization method, a bulk polymerization method, a solution polymerization method, and a suspension polymerization method may be used. In addition, the molecular weight of the obtained polymer can be adjusted by using a commonly used chain transfer agent such as hydrogen during the polymerization. When a polymerization solvent is used in a solution polymerization method, a slurry polymerization method, or the like, the solvent is not particularly limited as long as it is inert to the polymerization, and examples thereof include aromatic hydrocarbons such as benzene, toluene, and xylene. And aliphatic hydrocarbons such as pentane, hexane, heptane and octane, and alicyclic hydrocarbons such as cyclopentane and cyclohexane. Further, the polymerization temperature is usually 0 to 250 ° C. depending on the polymerization method.
The polymerization pressure is usually 0.01.
１００100 kg / cm ² G, preferably 0.2-60 kg / c
It may be appropriately selected in the range of m ² G. The polymerization time is usually about 1 minute to 10 hours.

[0016]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The evaluation of the physical properties of the propylene homopolymer was carried out in advance by using Irganox 1010 as an antioxidant.
Weight ratio of 1: 1 and BHT is 4000 weight pp
The addition of m was performed according to the following method. (1) Melt index MI ₅ , MI _2.16 Load according to ASTM D1238 at a temperature of 230 ° C.
MI _{5 at} 5.0 kg and MI _2.16 at _2.16 kg load were measured. (2) Melt tension MS Measured according to the method described in the text of the specification. (3) Intrinsic viscosity [η] It was measured in a tetralin solvent at a temperature of 135 ° C. (4) Melting point Tm Measured according to the method described in the text of the specification. (5) Weight average molecular weight Mw and molecular weight distribution Mw / Mn Measured according to the method described in the text of the specification.

EXAMPLE 1 400 ml of dehydrated toluene and 5 mmol of methylaluminoxane (toluene solution manufactured by Tosoh Agzo Co., Ltd.) were introduced into a 1.6-liter stainless steel pressure-resistant autoclave equipped with a stirrer under a nitrogen stream, and then 500 rpm in terms of aluminum atoms. , The temperature was raised to 90 ° C., and stirring was continued for 5 minutes. Thereto, rac- dimethylsilylene bis - (2-methyl-4-phenyl - indenyl) zirconium dichloride (rac-Me ₂ Si [2
-Me-4-Ph-Ind] ₂ ZrCl ₂ ) after 2 μmol of a toluene solution was added thereto, and propylene was continuously supplied at a gauge pressure of 2.0 kg / cm ² G.
Polymerization was performed for 0 minutes (first-stage reaction). Thereafter, the polymerization temperature was lowered to 60 ° C., and at the same time, propylene was continuously supplied at a gauge pressure of 7.0 kg / cm ² G.
Polymerization was carried out for 2 minutes (second stage reaction). After the completion of the reaction, unreacted propylene was removed by depressurization, the catalyst was deactivated with a small amount of methanol, and then a propylene homopolymer was recovered by filtration, and air-dried and vacuum-dried to obtain 117 g.
Was obtained. Table 1 shows the evaluation results of the physical properties of the propylene homopolymer.

Example 2 In Example 1, the first-stage reaction was carried out at a propylene pressure of 1.
The reaction was carried out under the conditions of 0 kg / cm ² G, a polymerization temperature of 85 ° C., and a polymerization time of 45 minutes.
84.0 g of a propylene homopolymer was obtained in the same manner as in Example 1 except that the polymerization was performed under the conditions of 0 kg / cm ² G, a polymerization temperature of 55 ° C., and a polymerization time of 30 minutes. Table 1 shows the evaluation results of the physical properties of the propylene homopolymer. Comparative Example Physical properties of a commercially available propylene-based polymer “Idemitsu Polypro E-185G” manufactured by Idemitsu Petrochemical Co., Ltd. were evaluated. Table 1 shows the results.

[0019]

[Table 1]

Note 1) logMS = 3.17 × log [η]
Calculated from −0.68 2) M ₅ / MI _2.16 = 0.240 × Mw / Mn + 3.1

[0021]

The propylene homopolymer of the present invention can control the melt tension and is suitable for foam molding, sheet molding, blow molding and the like. In addition, it has properties equal to or higher than conventional propylene-based polymers, and has excellent melt processing properties, and conventional propylene-based polymers have restricted use in molding methods such as large blow molding and extrusion foaming. Can be applied to

Claims (3)

[Claims] 1. A melt index MI ₅ (g / 10) at a load of 5.0 kg measured at a temperature of 230 ° C.
Min) and melt index MI _{2.16 at 2.16} kg load
The ratio MI ₅ / MI _2.16 of (g / 10 min), the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn measured by gel permeation chromatography is of the formula MI ₅ / MI _2.16 ≧ 0.240 × Mw / Mn + 3.1 (1) and (b) the melt tension MS (g) measured at a temperature of 230 ° C. and the limit measured at a temperature of 135 ° C. in a tetralin solvent. Viscosity [η] (dl /
g) satisfies the relationship of logMS ≧ 3.17 × log [η] −0.68 (II), and the intrinsic viscosity [η] is 0.1 to 15.0.
propylene homopolymer characterized by being in the range of dl / g. 2. The method according to claim 1, wherein Mw / Mn is 1.5 to 4.5.
The propylene homopolymer according to the above. 3. The propylene homopolymer according to claim 1, which has a melting point of 120 to 165 ° C. measured by a differential scanning calorimeter.