JPH04258652A - High-impact polypropylene resin composition - Google Patents

Abstract

PURPOSE:To improve impact resistance, transparency, and balance among physical properties by mixing a syndiotactic PP with an ethylene-propylene copolymer so as to give a mixture wherein both polymers are dissolved in each other. CONSTITUTION:30-98 pts.wt. copolymer of 10-95wt.% ethylene and 90-5wt.% propylene is mixed with 70-2 pts.wt. syndiotactic PP which has an intrinsic viscosity (135 deg.C, a tetralin soln.) of 0.1-10.0 and comprises a propylene homopolymer having a syndiotactic pentad fraction of at least 0.6 or a propylene-alpha-olefin copolymer having a peak intensity observed around 20.2ppm in 13C-NMR measured using a 1,2,4-trichlorobenzene soln. of at least 0.3 times the peak intensity assignable to all the methyl groups of propylene units, thus giving the title compsn. which does not have any peak of tan delta (in dynamic viscoelasticity analysis) assignable to the ethylene-propylene copolymer and in which both polymers are dissolved in each other.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to impact resistant polypropylene resin compositions. Specifically, the present invention relates to a polypropylene resin composition that is substantially composed of polypropylene having a syndiotactic structure and a copolymer of ethylene and propylene, and in which both are substantially compatible.

0002

[Prior Art] The existence of syndiotactic polypropylene has been known for a long time, but the conventional low-temperature polymerization method using a catalyst consisting of a vanadium compound, ether, and organoaluminum has poor syndiotacticity; It was hard to say that it represented the characteristics of polypropylene, and even more so, it was hard to say that the copolymer of ethylene and propylene was crystalline polypropylene. On the other hand, J. A. It was discovered for the first time by EWEN et al. that polypropylene with good tacticity, with a syndiotactic pentad fraction exceeding 0.7, could be obtained using a catalyst consisting of a transition metal catalyst component having an asymmetrical ligand and aluminoxane. (
J. Am. Chem. Soc. , 1988, 110, 6
255-6256).

0003

[Problem to be solved by the invention] The above J. A. EWEN
The method by et al. has good activity per transition metal, high tacticity of the polymer obtained, and relatively well-balanced physical properties of the polymer, but it has the problem of poor low-temperature impact resistance. was there.

0004

[Means for Solving the Problems] The present inventors solved the above-mentioned problems, searched intensively for a polypropylene composition that has excellent impact resistance, good transparency, and an excellent balance of physical properties, and completed the present invention. did.

That is, the present invention consists of a polypropylene having a substantially syndiotactic structure and a copolymer of ethylene and propylene, and furthermore, the tan δ which is assigned to the copolymer of ethylene and propylene in dynamic viscoelastic analysis is This is an impact-resistant polypropylene resin composition characterized in that no peak is observed.

[0006] Below, the composition of the present invention will be described in detail by explaining its manufacturing method. Examples of catalysts suitable for synthesizing polypropylene having a substantially syndiotactic structure, which is a component of the composition of the present invention, include the compounds described in the above-mentioned documents, but even if they have a different structure, propylene can be used alone. When a polymer is produced, the syndiotactic pentad fraction (A. Zambe
Macromolecules vol 6
687 (1973), vol 8 925 (19
75)) Any catalyst system can be used as long as it gives a polymer with relatively high tacticity of about 0.7 or more.
For example, a catalyst system consisting of a transition metal compound having an asymmetrical ligand and an organoaluminum is effective.

Examples of suitable catalyst systems include isopropyl (cyclopentadienyl-1-fluorenyl) hafnium dichloride, or isopropyl (cyclopentadienyl-1-fluorenyl) described in the above-mentioned literature.
Examples include zirconium dichloride, and examples of organoaluminum include aluminoxane and alkyl aluminum; examples of aluminoxane include those in the form of alkyl aluminum condensed with water; methylaluminoxane is particularly effective; 5 or more, preferably 10 or more are used.

The ratio of aluminoxane to the transition metal catalyst component used is 10 to 1,000,000 times by mole, usually 50 to 5,000 times by mole. Also, a combination of an alkyl aluminum and a stable anion, or a compound that generates it, can be used.

[0009] There are no particular limitations on the polymerization conditions, and solvent polymerization using an inert medium, bulk polymerization in which an inert medium is not substantially present, and gas phase polymerization can also be used. Generally, the polymerization temperature is -100 to 200°C, and the polymerization pressure is normal pressure to 100 kg/cm2. Preferably -100 to 100°C, normal pressure to 50k
g/cm2.

[0010] Furthermore, during polymerization, ethylene or α-olefins having 4 or more carbon atoms, such as butene-1, pentene-1, hexene-1, heptene-1, are added in an amount of 10% by weight or less.
It is possible to copolymerize 1,4-methylpentene-1, but if it is more than 10% by weight, the physical properties of the composition will be poor, which is not preferred.

Here, the term "substantially syndiotactic structure" refers to a propylene homopolymer having a syndiotactic pentad fraction of 0.6 or more, preferably 0.7 or more; If it is smaller than .6, the characteristics as crystalline polypropylene are insufficient and the physical properties are poor, which is not preferable.

In addition, in the case of copolymers with other α-olefins, the peak intensity observed at about 20.2 ppm in 13C-NMR measured with a 1,2,4-trichlorobenzene solution is the total methyl of propylene units. The peak intensity attributable to the group is 0.3 or more, preferably 0.5 or more, and if it is less than 0.3, the physical properties are poor and undesirable. The molecular weight is about 0.1 to 20, preferably about 0.5 to 10, as the intrinsic viscosity measured in a tetralin solution at 135°C.

The ethylene and propylene copolymer used in the present invention preferably has an ethylene content of 10 to 95 wt%, and if it is outside this range, it will not be effective in improving impact resistance. Here, it is also possible to replace a part of the ethylene with an α-olefin having 4 or more carbon atoms, but the amount thereof is at most half the amount of ethylene.

The copolymer used in the present invention needs to be well compatible with the polypropylene having a syndiotactic structure, and for this purpose, it is preferable that the propylene chains in the copolymer be racemic. The degree of racemicity is expressed by the racemic fraction of two or three consecutive propylene units when looking at six monomer units in the polymer chain, and this structure can be determined by 13C-NMR. For example, Polymer, reported by Asakura et al.
Details are given in 1988, vol 29 2208. The molecular weight of the copolymer is about 0.1 to 20, preferably about 0.5 to 10, as the intrinsic viscosity measured in a tetralin solution at 135°C.

[0015] A catalyst suitable for producing the copolymer is one in which, when the propylene is polymerized, the resulting polymer has a highly syndiotactic structure and has good copolymerizability with ethylene. Examples include things like: Specifically, the catalyst system described above is used, and the polymerization conditions described above can be used as they are.

In the present invention, the quantitative ratio of the substantially syndiotactic polypropylene to the copolymer of ethylene and propylene is about 30/70 to 98/2, more preferably about 45/55 to 95/5. . 30/70
If it is smaller, the rigidity is poor, and if it exceeds 98/2, the impact resistance is poor.

The composition of the present invention can also be prepared by mixing the above two components using a kneader capable of good mixing. In addition, it can be produced by a so-called block copolymerization method in which propylene is first polymerized and then ethylene and propylene are copolymerized, but in order to obtain the composition of the present invention, it is necessary to further knead the copolymer. It is.

As the kneading machine used for producing the composition of the present invention, one that is capable of relatively strong kneading is preferably used, and an extruder equipped with twin screws, a Banbury type kneading machine, etc. are used. can. The kneading temperature is 15
The temperature is 0 to 350°C, preferably 180 to 300°C, and the degree of kneading is determined by measuring the glass transition temperature by dynamic viscoelasticity analysis and determining the extent to which no transition attributed to the copolymer of ethylene and propylene is observed. It is necessary to do so.

[0019] Here, the fact that no metastasis is observed means that, for example,
When measured by dynamic mechanical thermal analysis, the peak of tan δ attributed to the copolymer of ethylene and propylene is about 1/3 or less of that before mixing.

Since the composition of the present invention is uniformly mixed, when a section is observed under an electron microscope, no so-called sea-island structure is observed.

[0021]

[Examples] The present invention will be further explained by showing examples below.

Example 1 Isopropylcyclopentadienyl-1-fluorene, which was synthesized according to a conventional method in an autoclave with an internal volume of 7 liters, was lithiated, reacted with zirconium tetrachloride, and purified by recrystallization. Dissolve 15 mg of zirconium dichloride (pentadienyl-1-fluorenyl) and 2 g of methylaluminoxane (polymerization degree 16.1) manufactured by Tosoh Akzo Co., Ltd. in 3 liters of toluene, and add propylene to 4 kg/cm2-G at 20°C. and polymerized for 1 hour while adding propylene to 4 kg/cm2-G, then 0.5 kg
/cm2-G, a part of the slurry was collected, filtered and dried, dissolved in 1,2,4-trichlorobenzene, and analyzed by 13C-NMR. The proportion of syndiotactic pentads was 0.93
Met.

[0023] Then, 3 kg/cm2-G of ethylene
The mixture was added so as to be polymerized for 20 minutes. After polymerization, unreacted monomers were purged and the powder obtained was washed with 1 liter of hexane five times and dried under reduced pressure at 80°C to give 2.
20 g of polymer was obtained.

Analysis by 13C-NMR showed that the ethylene content was 12.4 wt% and the syndiotactic pentad ratio was 0.78. Also, 135℃
Intrinsic viscosity measured with tetralin solution (hereinafter referred to as η)
was 1.24, and the ratio of weight average molecular weight to number average molecular weight (hereinafter referred to as MW/MN) measured in a 1,2,4-trichlorobenzene solution at 135°C was 6.7. The ratio of the copolymer to the total polymer calculated from the slurry concentrations before and after starting the copolymerization of ethylene and propylene is 32 wt%, and therefore the ethylene content of the copolymer can be estimated to be 41 wt%. This powder was press-molded at 200°C to produce a 2 mm sheet, and the following physical properties were measured.・Bending rigidity: kg/cm2 ASTM D7
47 (23℃) ・Tensile yield strength: kg/cm2
ASTM D638 (23℃)・Elongation:%
ASTM D638 (2
3℃)・Izod (with notch) Impact strength: kg・c
m/cm ASTM D256 (23℃, -10℃) ・Haze:% ASTM
Compliant with D1003.

[0025] Bending rigidity is 2600 kg/cm2, tensile yield strength is 120 kg/cm2, and elongation is 250.
%, Izod impact strength is 61, 15.6 (2
3°C, -10°C) kg·cm/cm, and the haze was 78%. Dynamic viscoelasticity measuring device (hereinafter referred to as DM) manufactured by Seiko Electronics Co., Ltd. (SDM5500) of this sheet
-100 to 150 at 0.5Hz using
The glass transition temperature (measured as the peak of tan δ) measured by increasing the temperature from ℃ to 2℃/min was 8.5℃, -
The temperature was 42.5°C.

[0026] This copolymer was further heated at 210°C (
After kneading at 100 rpm), a sheet was similarly prepared and its physical properties were measured, and the bending rigidity was 3000 kg/c.
m2, tensile yield strength was 139 kg/cm2, elongation was 323%, Izod impact strength was 61 and 64 kg·cm/cm (at 23°C and -10°C, respectively), and haze was 71%. Further, the glass transition temperature measured by DMA showed a single peak at -1.2°C.

Comparative Example 1 Polymerization without using ethylene, η1.38, syndiotactic pentad ratio 0.93, MW/MN
When a polymer with 2.1 was obtained and the physical properties were measured in the same manner as in Example 1, the bending stiffness was 7700 kg/
cm2, tensile yield strength is 278 kg/cm2, elongation is 250%, Izod impact strength is 63.1, 3.
7 (23°C and -10°C, respectively) kg·cm/cm, and the haze was 58%.

Example 2 Using the catalyst obtained in Example 1, 0.5 kg of propylene
/cm2-G and further ethylene at 3kg/cm2-
G Add a copolymer of ethylene and propylene at 20℃
Manufactured by. The η of this copolymer was 0.88. 20 parts by weight of this copolymer and 70 parts by weight of the syndiotactic polypropylene obtained in Comparative Example 1 were mixed in the same manner as in the extruder used in Example 1 to obtain a composition. The physical properties of this composition were as follows. Bending rigidity is 4500kg/cm
2. The tensile yield strength was 157 kg/cm2, the elongation was 240%, the Izod impact strength was 61 and 48 kg·cm/cm (at 23°C and -10°C, respectively), and the haze was 66%. Further, the glass transition temperature measured by DMA showed a single peak at -1.8°C.

[0029]

[Effects of the Invention] The copolymers and compositions of the present invention have excellent impact resistance and an extremely good balance of physical properties.
It is extremely valuable industrially.

Claims (1)

[Claims] Claim 1: Consisting of polypropylene having a substantially syndiotactic structure and a copolymer of ethylene and propylene, and furthermore, a tan δ peak attributed to the copolymer of ethylene and propylene was observed by dynamic viscoelastic analysis. An impact-resistant polypropylene resin composition characterized in that it is not