JPH02173015A - Random propylene copolymer and its production - Google Patents

Abstract

PURPOSE:To obtain the title copolymer improved in heat sealability, blocking resistance and rigidity by copolymerizing propylene with ethylene and an alpha-olefin in the presence of a catalyst prepared from a specified Hf compound and an aluminooxane. CONSTITUTION:Propylene is copolymerized with ethylene and a 4-20C alpha-olefin such as 1-butene at 40-100 deg.C in the presence of a catalyst containing an Hf compound having, as ligands, a polydentate coordination compound in which at least two groups selected form cycloalkadienyl groups and derivatives thereof are bonded to the Hf atom through lower alkylene groups in such an amount as to give 10<-8>-10<-2>g Hf atoms/l and 10<-4>-10<-1>g Al atoms/l. In this way, a random copolymer comprising 90-99mol.% propylene units, 0.5-9.5mol.% ethylene units and 0.5-9.5mol.% alpha-olefin units (4-20C) and having an intrinsic viscosity of 0.5-6dl/l as measured in decalin at 135 deg.C, satisfying 70<m.p.[Tm]<155-5.5 (100-P) (wherein P is the content of propylene) and having a content of boiling trichloroethylene-insolubles <=5wt.% can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a novel propylene random copolymer and a method for producing the same. The present invention particularly relates to a novel propylene-based random copolymer with excellent heat-sealing properties and anti-blocking properties, and a method for producing the same.

Technical background of the invention and its problems Polypropylene has excellent physical properties, so
It is used for a wide range of purposes. For example, polypropylene is widely used as a packaging film, but since polypropylene has a relatively high melting point, in order to improve heat-sealability at low temperatures in this type of application, propylene is generally mixed with ethylene or carbon atoms with 4 to 20 carbon atoms. α−
It is used as a propylene/α-olefin copolymer by copolymerizing olefins.

Conventionally known packaging films made of propylene/α-olefin copolymers have superior transparency and scratch resistance compared to films made of low-density polyethylene, but they still have poor heat sealability at low temperatures. However, the development of a propylene/α-olefin copolymer with excellent heat sealability at low temperatures is desired.

It is known that in order to improve the heat sealability of the propylene/α-olefin random copolymer described above, it is sufficient to increase the copolymerization amount of ethylene or α-olefin having 4 to 20 carbon atoms with respect to propylene. Although,
If the copolymerization amount of ethylene or α-olefin having 4 to 20 carbon atoms is increased, the resulting propylene/α-
Olefin copolymers have a large amount of solvent soluble content, resulting in poor blocking resistance and poor rigidity.

In order to obtain a propylene/α-olefin random copolymer with excellent heat sealability, blocking resistance, and rigidity at low temperatures, it is necessary to have a low melting point despite the small amount of α-olefin copolymerized. propyleneΦα
- The emergence of olefin random copolymers is necessary.

Conventionally, olefin polymerization catalysts consisting of titanium or vanadium compounds and organic aluminum compounds have been used to produce propylene/α-olefin random copolymers, but in recent years, zirconium compounds have been used as new Ziegler-type olefin polymerization catalysts. Catalysts consisting of and aluminoxane have recently been proposed.

JP-A No. 58-19309 describes the following formula % formula % [where R is cyclopentadienyl, 01 to C6 alkyl, halogen, Me is a transition metal, Ha
p is halogen] and a transition metal-containing compound represented by the following formula %)) [where R is methyl or ethyl and n is 4 to 2
In the presence of a catalyst consisting of a linear aluminoxane represented by the number 0] or a cyclic aluminoxane represented by the following formula [where R and n are the same as above], ethylene and A method is described in which one or more C3 to C12 α-olefins are polymerized at temperatures of 150°C to 200°C. The publication states that in order to adjust the density of the resulting polyethylene, the polymerization of ethylene should be carried out in the presence of small amounts of up to 10% by weight of somewhat long-chain α-olefins or mixtures. .

JP-A No. 59-95292 describes a linear aluminoxane represented by the following formula, [where n is 2 to 40, and R is C-CB] and a linear aluminoxane represented by the following formula [where n and The invention relates to a method for producing a cyclic aluminoxane represented by [the definition of R is the same as above]. The publication states that when olefin polymerization is carried out by mixing, for example, methylaluminoxane and a titanium or zirconium bis(cyclopentagenyl) compound produced by the same production method, It is stated that more than 25 million g of polyethylene can be obtained per hour.

JP-A No. 60-35005 describes the following formula [where,
R is C-CIo alkyl, ■ R is R1 or combined to represent 10-] is first reacted with a magnesium compound, then the reaction product is chlorinated, and Treated with a compound of “l”l 5VSZr or C”,
A method of making a polymerization catalyst for olefins is disclosed. The same publication states that the catalyst is ethylene and α of 03 to C12.
- are described as being particularly suitable for the copolymerization of mixtures of olefins.

JP-A-60-35006 discloses that two or more different transition metal mono- or tricyclopentadienyl or derivatives thereof (a) and aluminoxane (b) are used as a catalyst system for producing a reactor blend polymer. ) combinations are disclosed. In Example 1 of the same publication, ethylene and propylene were polymerized using bis(pentamethylcyclopentadienyl)zirconium dimethyl and aluminoxane as catalysts, and the number average molecular weight was 1.5,300. Weight average molecular weight 36,400 and propylene component 3.4
% polyethylene was obtained.

In addition, in Example 2, ethylene and propylene were polymerized using bis(pentamethylcyclopentadienyl)zirconium dichloride, bis(methylcyclopentagenyl)zirconium dichloride, and aluminoxane as catalysts, and the number average molecules fjk2, 200, from a toluene soluble part containing a weight average molecular weight of 11.900 and a propylene component of 30 mol% and a toluene insoluble part containing a number average molecular weight of 3.000, a weight average molecular weight of 7,400 and a propylene component of 4.8 mol%. The number average molecular weight becomes 2,
000, weight average molecular weight 8,300 and 7.1 mol%
A blend of polyethylene and ethylene-propylene copolymer containing a propylene component of Similarly, in Example 3, LLDPE and ethylene consisting of a soluble portion with a molecular weight distribution (My/Mn) of 4.57 and a propylene component of 20.6% and an insoluble portion with a molecular weight distribution of 3.04 and a propylene component of 2.9 mol% were used. - Blends of propylene copolymers are described.

JP-A No. 60-35007 discloses that ethylene alone or together with an α-olefin having 3 or more carbon atoms is used with metallocene and the following formula [where R is an alkyl group having 1 to 5 carbon atoms, and n is 1 a cyclic aluminoxane represented by the following formula % [wherein the definitions of R and n are the same as above]: A method for polymerization in the presence of is described.

According to the description in the same publication, the polymer obtained by this method has a weight average molecular weight of about 500 to about 1.4 million, and a molecular weight distribution of 1.5 to 4.0.

In addition, JP-A No. 60-35008 discloses that by using a catalyst system containing at least two types of metallocene and aluminoxane, [[1 polyethylene or ethylene having a wide molecular weight distribution and an α-olefin of 03 to C1o]. It is described that a copolymer of The publication states that the above copolymer has a molecular weight distribution (Mv /Mn) of 2 to
It is described that it has 5o.

Furthermore, JP-A-61-130314 discloses that polypropylene with a high degree of isotacticity can be obtained by polymerizing propylene in the presence of a catalyst system consisting of a sterically fixed zircon-chelate compound and aluminoxane. Are listed.

Furthermore, J,Am,Chem,Soc,, 109.6
544 (1987), ethylenebis(indenyl)
When propylene is polymerized in the presence of a catalyst system consisting of hafnium dichloride or its hydride and aluminoxane, high molecular weight isotactic polypropylene is produced, with a sono molecular weight distribution (My/K11n) of 2.1 to
It is stated that it is as narrow as 2.4.

On the other hand, Japanese Patent Application Laid-Open No. 63-142005 discloses that M
It is described that stereoblock polypropylene having a y/Mn of 560 to 14.9 can be obtained. The propylene obtained here is a rubbery polymer with a short isotactic chain length.

The present inventors have found that if propylene and an α-olefin having 4 to 20 carbon atoms are copolymerized in the presence of an olefin polymerization catalyst consisting of a specific hafnium compound and aluminoxane, the amount of copolymerized α-olefin can be increased. The present inventors have discovered that a propylene-based random copolymer having a lower melting point than conventionally known propylene/α-olefin copolymers can be obtained despite having a small amount of olefin, and has completed the present invention.

Purpose of the Invention The present invention aims to solve the problems in the prior art as described above, and has a low melting point despite the small amount of copolymerization of ethylene and α-olefin.
The object of the present invention is to provide a propylene-based random copolymer that has excellent heat-sealability, blocking resistance, and rigidity, and a method for producing the same.

Summary of the Invention The propylene random copolymer according to the present invention comprises a structural unit (a) derived from propylene, a structural unit (b) derived from ethylene, and a structural unit derived from an α-olefin having 4 to 20 carbon atoms ( C) a propylene random copolymer consisting of (A) the structural unit (a) in an amount of 90 to 99 mol% and the structural unit (b) in an amount of 0.5
~9.5 mol %, and the structural unit (c) is 0.
present in an amount of 5 to 9.5 mol%; (B) intrinsic viscosity [η] measured in decalin at 135°C;
is in the range of 0.5 to 6 dl/g, (C) Melting point [Tm] measured by differential scanning calorimeter
is in the range of 70<Tm<155-5.5 (100-P) (where P is the propylene component content (mol%) in the copolymer), and (D) the amount of boiling trichlorethylene insolubles is 5 % by weight or less.

Further, the method for producing a propylene random copolymer according to the present invention includes (A) a polydentate coordination in which at least two groups selected from cycloalkagenyl groups or substituted products thereof are bonded via a lower alkylene group; In the presence of a hafnium compound having the compound as a ligand and a catalyst formed from (B) aluminoxane, propylene, ethylene, and an α-olefin having 4 to 20 carbon atoms are added to the resulting copolymer. The structural unit (a) derived from propylene is 90
In an amount of ~99 mol%, structural units derived from ethylene (
c) is in an amount of 0.5 to 9.5 mol%, and the structural unit (c) derived from an α-olefin is 0.5 to 9.5 mol%.
It is characterized in that it is copolymerized so that it is present in an amount of

DETAILED DESCRIPTION OF THE INVENTION The propylene random copolymer and the method for producing the same according to the present invention will be specifically described below.

The propylene random copolymer according to the present invention is a random copolymer of propylene, ethylene, and an α-olefin having 4 to 20 carbon atoms. In this propylene-based random copolymer, the structural unit derived from propylene (a
) is present in an amount of 90 to 99 mol%, preferably 92 to 98 mol%, and the structural unit (b) derived from ethyline is 0
．． The structural unit (C) is present in an amount of 5 to 9.5 mol%, preferably 1 to 9 mol%, and the structural unit (C) derived from an α-olefin is present in an amount of 0.5 to 9.5 mol%, preferably 1 to 9 mol%. It is desirable that it be present in an amount of When the structural unit (a) derived from propylene in the copolymer is less than 90 mol%,
The blocking resistance and stiffness of the copolymer tend to be poor. On the other hand, if it exceeds 99 mol%, the melting point of the copolymer will become high and the heat sealability will tend to be poor.

The α-olefins having 4 to 20 carbon atoms used in the present invention include 1-butene, ■-pentene, 1-hexene,
-methyl-1-pentene, 3-methyl-1-pentene,
1-octene, ■-decene, ■-dodecene, ■-tetradecene, 1-hexadecene, ■-octadecene, ■-eicosene, etc. are used. Among these, l-butene is particularly preferred.

Further, the propylene random copolymer according to the present invention has 1
Intrinsic viscosity [η] measured in decalin at 35°C is 0.5
It is desirable that it is in the range of ~6 dll/g, preferably 1 ~ 5 dN/g. If the intrinsic viscosity is less than 0.5 dD/z, the blocking resistance and rigidity of the copolymer tend to be poor, which is undesirable. On the other hand, if it exceeds 6 dll/g, moldability tends to be poor, which is not preferred. .

Furthermore, the propylene random copolymer according to the present invention is
The melting point [Ti] measured by a differential scanning calorimeter is 70<Ta+<155-5.5 (100-P), preferably 90<Tm<150-5.5 (100-P) (where P is copolymer The propylene component content (mol %) in the coalescence is within the range of

A schematic relationship between the melting point Tm of such a propylene-based random copolymer and the propylene component content P mol % in the copolymer is shown as a straight line A in FIG. In addition, in FIG. 1, the relationship between the melting point TffI of a conventionally known propylene/α-olefin random copolymer and the propylene component content P mol % is also shown as a straight line B.

As is clear from FIG. 1, when the copolymerization amounts of ethylene and α-olefin are the same, the melting point of the propylene-based random copolymer according to the present invention is different from that of the conventionally known propylene-α-olefin random copolymer. 10 to 20°C lower than the melting point of the copolymer. Therefore, the film obtained from the propylene random copolymer according to the present invention has excellent heat-sealability, especially at low temperatures. Moreover, since the amount of copolymerization of ethylene and α-olefin at least shows excellent heat sealing properties, it also has excellent blocking resistance and also has excellent rigidity.

In addition, in the present invention, using a differential scanning calorimeter (DSC),
The propylene random copolymer was left at 200°C for 5 minutes, then cooled to 20°C at a rate of 10°C/min, then left at 20°C for 5 minutes, and then cooled to 20°C at a rate of 10°C/min.
The temperature (Tm) of the maximum endothermic peak obtained by raising the temperature from 200°C to 200°C was taken as the melting point of the propylene random copolymer.

Further, the molecular weight distribution (My/Mn) of the propylene random copolymer according to the present invention determined by gel permeation chromatography (GPC) is 3.5 or less, preferably 3.
, 0 or less, particularly preferably 2.5 or less. As described above, the propylene random copolymer according to the present invention is
It has a narrow molecular weight distribution and has excellent blocking resistance in this respect as well.

The My/Mn value was determined as follows based on "Gel Permeation Chromatography" written by Takeuchi and published by Maruzen.

(1) Using standard polystyrene with a known molecular weight (manufactured by Toyo Soda ■, monodisperse polystyrene), calculate the molecular weight M and its G.
P C (Gel PerIIation Chro
matograph) counts and molecular weights M and E
A correlation diagram calibration curve of V (EluttonVolume) is created. The concentration at this time is 0.02% by weight.

(2) Obtain a GPC chromatograph of the sample by GPC measurement, calculate the number average molecular weight Mns and weight average molecular weight Mw in terms of polystyrene according to the above (1), and obtain the MwZMn value. Sample preparation conditions and G P Ci
The lJ constant conditions are as follows.

[Sample Preparation] (a) Disperse the sample in an Erlenmeyer flask together with 0-dichlorobenzene solvent to a concentration of 0.1% by weight.

(b) Heat the Erlenmeyer flask to 140°C and stir for about 30 minutes to dissolve.

(c) Subject the solution to GPC.

[G P Cδ-1 constant conditions] It was conducted under the following conditions.

(a) Equipment Manufactured by Waters (150cmAL
C/GPC) (b) Column manufactured by Toyo Soda (GMH
Type) (c) Sample amount 400μg (d) Temperature 140℃ (e) Flow rate 1ml/min Melting point measurement was performed using Perkln Ela+er-7 type DS
The measurement was carried out using a C apparatus with a sample quantity of 2.5 mg and a heating rate of 10° C./min.

The propylene random copolymer according to the present invention has a boiling n
- It is desirable that the soluble portion in pentane is 5% by weight or less, preferably 3% by weight or less, more preferably 2% by weight or less.

Furthermore, the propylene random copolymer according to the present invention is
It is desirable that the amount of insoluble face relative to boiling trichlorethylene is 5% by weight or less, preferably 3% by weight or less, and more preferably 1% by weight or less.

To determine the amount of boiling trichlorethylene insoluble matter and boiling n-penkneum soluble matter, put 3 g of a finely ground sample into a thimble filter paper, extract with a Soxhlet extractor using 180 ml of solvent for 5 hours, and extract the extracted residue with a vacuum dryer. The sample was dried until it reached a constant weight, and its weight was calculated based on the difference in weight from the original sample.

The propylene random copolymer according to the present invention as described above has (A) a polydentate coordination in which at least two groups selected from cycloalkagenyl groups or substituents thereof are bonded via a lower alkylene group. In the presence of a hafnium compound having the compound as a ligand and a catalyst formed from (B) aluminoxane, propylene, ethylene, and an α-olefin having 4 to 20 carbon atoms are mixed with 40 to 100 carbon atoms.
At a temperature of °C, the amount of the structural unit (a) derived from propylene in the obtained copolymer is 90 to 99 mol%, and the amount of the structural unit (b) derived from ethylene is 0.5 to 9.5 mol%.
, and also the constituent units derived from α-olefins (C
) is present in an amount of 0.5 to 9.5 mol % by copolymerization.

The catalyst component [A] used in the present invention is a cycloalkagenyl group or a substituted product thereof, specifically, at least two groups selected from the group consisting of an indenyl group, a substituted indenyl group, and a partially hydrogenated product thereof. It is a hafnium compound whose ligand is a polydentate compound in which groups are bonded via lower alkylene groups. The following compounds can be exemplified as the hafnium compound.

Ethylenebis(indenyl)dimethylhafnium, ethylenebis(indenyl)diethylhafnium, ethylenebis(indenyl)diphenylhafnium, ethylenebis(indenyl)methylhafnium monochloride, ethylenebis(indenyl)ethylhafnium monochloride, ethylenebis(indenyl)methyl Hafnium monochloride, ethylene bis(indenyl) hafnium compound lide, ethylene bis(indenyl) hafnium compound lide, ethylene bis(4,5,6,7-tetrahydro-1-indenyl)dimethyl hafnium, ethylene bis(4,5) , 6,7-tetrahydro-1-indenyl) methyl hafnium monochloride, ethylenebis(4,5,8,7-tetrahydro-1-indenyl)
Hafnium dichloride, ethylenebis(4,5,6,7-tetrahydro-1-indenyl)hafnium dichloride, ethylenebis(4-methyl-1-indenyl)no\fnium dichloride, ethylenebis(5-methyl-1-indenyl) ) hafnium dichloride, ethylene bis(6-methyl-1-indenyl) hafnium dichloride, ethylene bis(7-methyl-1-indenyl) hafnium dichloride, ethylene bis(5-methoxy-1-indenyl) hafnium dichloride, ethylene bis(2 ,3-dimethyl-1-indenyl) hafnium dichloride, ethylenebis(4,7-dimethyl-1-indenyl)hafnium dichloride, ethylenebis(4,7-simethoxy-indenyl)
Hafnium dichloride.

The catalyst component [B] used in the method of the invention is an aluminoxane. As the aluminoxane used as a catalyst component, the oxyorganoaluminum compound represented by the general formula (I) or the -format (II) is preferably a hydrocarbon group such as a methyl group, preferably a methyl group or an ethyl group, and particularly preferably a methyl group or an ethyl group. is a methyl group, and m is an integer of 2 or more, preferably 5 or more. Examples of the method for producing the aluminoxane include the following method.

(1) Compounds containing adsorbed water, salts containing water of crystallization, such as magnesium chloride hydrate, copper sulfate hydrate, aluminum sulfate hydrate, nickel sulfate hydrate, monochloride
A method of adding trialkylaluminium to a suspension in another hydrocarbon medium such as cerium hydrate and causing a reaction.

(2) A method in which water, steam, or ice is directly applied to trialkylaluminium in a medium such as benzene, toluene, ethyl ether, or tetrahydrofuran.

Note that the aluminoxane may contain a small amount of organometallic component.

The hafnium compound as described above is used in an amount of usually 10-8 to 10-2 gram atom/II, preferably 10-7 to 10-3 gram atom/g as the concentration of the hafnium atom in the polymerization reaction system. It is desirable that

Further, the aluminoxane as described above is used in an amount of 10-4 to 10-1 gram atom/g, preferably 5 x 10-' to 5 x 10-2 gram atom/Ω in terms of aluminum atoms in the reaction system. It is desirable that it be used.

Polymerization temperature is usually 40-100°C, preferably 45-95°C.
℃, more preferably in the range of 50 to 90℃.

The polymerization of olefins as described above is usually carried out in a gas phase or a liquid phase. In liquid phase polymerization, an inert hydrocarbon may be used as a solvent, or the olefin itself may be used as a solvent.

Hydrocarbon media specifically include butane, isobutane, pentane, hexane, octane, decane, dodecane,
Aliphatic hydrocarbons such as hexadecane and octadecane,
Alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, and cyclooctane, aromatic hydrocarbons such as benzene, toluene, and xylene, and petroleum fractions such as gasoline, kerosene, and kerosene are used.

The polymerization pressure is usually from normal pressure to 100 kg/cd, preferably from normal pressure to 50 kg/c, and the polymerization can be carried out in any of the batch, semi-continuous and continuous methods. The molecular weight of the polymer can be controlled by hydrogen and/or polymerization temperature.

Effects of the Invention According to the present invention, a novel propylene-based random copolymer has a narrow molecular weight distribution and a low melting point even at low α-olefin and ethylene contents compared to conventionally known propylene/α-olefin random copolymers. A copolymer and a method for producing the same are provided, and this copolymer has excellent heat-sealability, as well as excellent blocking resistance and rigidity.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 (Preparation of methylaluminoxane) Polymer Coamun, 29.180 (19
Prepared according to H).

(Synthesis of ethylene bis(indenyl) hafnium dichloride) Bis(indenyl)ethane (Bi II, Soc, Chlm
, 2954 (1987)) 5.4
g and 50 ml of THF, and while stirring -3
It was cooled to 0 to -40°C. To this, n-Bu Ll
Add 31.5 ml (1.6M solution) dropwise, and then
After stirring at 0°C for 1 hour, bis(indenyl)ethane was anionized by naturally raising the temperature to room temperature. Add TI(F) to another 200 ml glass flask purged with nitrogen.
After charging 60 ml and cooling to below -60°C, Hf' (1!
6.7g was added gradually. Thereafter, the temperature was raised to 60°C and stirred for 1 hour. The anionized ligand was added dropwise to the mixture, stirred at 60°C for 2 hours, and then filtered through a glass filter. The filtrate was concentrated to about 1/5 of its original volume at room temperature. This operation precipitates a solid. The precipitated solid was filtered through a glass filter, washed with hexane/ethanol, and dried under reduced pressure to obtain the target compound.

(Polymerization) A mixed gas was prepared so that the propylene, -butene and ethylene gas compositions were 96.7.2.1.1.2 mol%, respectively. 500 ml of toluene was charged into a stainless steel autoclave No. 21 which had been sufficiently purged with nitrogen, and after cooling to 0° C., 3 moles of the above-prepared mixed gas and 5 milligram atoms of methylaluminoosane (calculated as Aj7 atoms) were charged.

Thereafter, the temperature of the polymerization system was raised to 45° C., 1.25-3×10 mol of ethylene bis(indenyl) hafnium dichloride was added, and polymerization was carried out at 50° C. for 0.5 hours. Polymerization was stopped by adding methanol to the polymerization system. The obtained polymer slurry was poured into a large amount of methanol, and then collected by filtration.
Furthermore, the catalyst component was removed using an isobutyl alcohol/hydrochloric acid solution.

Thereafter, by drying under reduced pressure at 80°C and 200 to 30C1+mHg overnight, the ■-butene content was 1.4 mol%, the ethylene content was 1.1 mol%, and 11-1 in decalin at 135°C. The determined Cη is 3.32 6B/
1, the melting point by DSC is 121°C, the amount of boiling trichlorethylene insoluble matter is 0% by weight, and the boiling n-
51.3 g of a polymer having a penkun soluble content of 0.069% by weight and a My/Mn of 2.45 by GPC was obtained.

Example 2 Polymerization was carried out in the same manner as in Example 1, except that the molar ratio of propylene, l-butene and ethylene was 95.1/3.9/1.0, and the l-butene content was 2
．． 7 mol%, ethylene content is 0.8 mol%, [η] is 3.29d, 07g, and melting point is 118°C
48.5 g of a polymer was obtained in which the amount of boiling trichlorethylene insoluble matter was 0% by weight, the boiling n-pentane soluble content was 1.1% by weight, and My/Mn was 2.40.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the propylene content and the melting point of the propylene/α-olefin random copolymer according to the present invention. Line B shows the relationship between the propylene content and melting point of a conventionally known propyline Φα-olefin random copolymer. be.

Claims (1)

[Claims] 1) A structural unit (a) derived from propylene, a structural unit (b) derived from ethylene, and α having 4 to 20 carbon atoms.
- A propylene-based random copolymer consisting of a structural unit (c) derived from an olefin, wherein (A) the structural unit (a) is in an amount of 90 to 99 mol%, and the structural unit (b) is
) in an amount of 0.5 to 9.5 mol%, and the structural unit (
c) is present in an amount of 0.5 to 9.5 mol%; (B) has an intrinsic viscosity [η] measured in decalin at 135°C;
is in the range of 0.5 to 6 dl/g, and (C) has a melting point [Tm] measured by a differential scanning calorimeter of 70<Tm<155-5.5 (100-P) (where P is copolymer A propylene-based random copolymer, characterized in that: (D) the amount of boiling trichlorethylene insoluble matter is 5% by weight or less; 2) (A) A hafnium compound whose ligand is a polydentate compound in which at least two groups selected from cycloalkadienyl groups or substituents thereof are bonded via a lower alkylene group, and (B) In the presence of a catalyst formed from aluminoxane, propylene, ethylene, and an α-olefin having 4 to 20 carbon atoms are mixed, so that the resulting copolymer contains 90 structural units (a) derived from propylene.
In an amount of ~99 mol%, structural units derived from ethylene (
Copolymerizing so that b) is present in an amount of 0.5 to 9.5 mol% and the structural unit (c) derived from the α-olefin is present in an amount of 0.5 to 9.5 mol%. A method for producing a propylene random copolymer, characterized by: