JPS5815548A - Polypropylene composition - Google Patents

Abstract

PURPOSE:To provide a polypropylene molding compsn. excellent in impact whitening, resistance impact resistance, luster and rigidity, prepared by adding specified polyethylene and specified amorphous ethylene/propylene random copolymer to a crystalline propylene polymer. CONSTITUTION:The compsn. consists of 46-64wt% polypropylene with an isotacticity index of 89 or higher, 1-17wt% ethylene/propylene random copolymer with a propylene unit content of 40-85mol% and 36-50wt% polyethylene with a limiting viscosity of 2.6dl/g or lower, to make a total of 100wt%. Molding products made of the compsn. are excellent in resistances to low temp. impact and whitening under impact, luster and rigidity and are suitable for automobile parts such as battery case and trim-pannel and parts of household electric appliances such as cleaner housing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding polymer composition that has excellent impact whitening resistance, gloss, and impact resistance, especially impact resistance at low temperatures, and has rigidity.

Crystalline polypropylene has excellent properties in terms of rigidity, heat resistance, and gloss, but its impact strength, especially at low temperatures, is low, making it difficult to apply to fields that require impact resistance at low temperatures. Met. In order to improve this point, a method of melt-kneading crystalline polypropylene with low-density polyethylene, high-density polyethylene, or ethylene-propylene random copolymer, etc.A so-called propylene block copolymer is produced by copolymerizing ethylene and propylene in multiple steps. As a result, impact strength has been improved and it has come to be widely used in fields such as automobile parts, industrial parts, containers, and household appliance parts.

Depending on their use, they are often subjected to secondary processing such as bending or subjected to impact from external forces, and as a result, areas where stress is concentrated often turn white, reducing their commercial value. Crystalline propylene-based polymers such as propylene homopolymer or propylene/α-olefin random copolymer have very good impact whitening resistance and pose no practical problems, but as mentioned earlier, impact resistance inferior to However, if a rubber material such as polyethylene or ethylene-propylene random copolymer is simply added to improve impact resistance, whitening may occur. Obtaining the composition was difficult.

As a result of intensive studies to improve these drawbacks, the present inventors have decided to blend a specific polyethylene and a specific non-quality ethylene/propylene random copolymer into a crystalline propylene polymer. It has been found that a propylene composition having excellent impact whitening resistance and impact resistance, as well as excellent gloss and rigidity can be obtained, and the present invention has been achieved.

That is, the present invention comprises (A) 46 to 64% by weight of polypropylene having an isotactic index of 89 or more; (B) 1 to 7% by weight of an ethylene-propylene random copolymer having 40 to 85 mol% of propylene units;
and (0) 36 to 50% by weight of polyethylene with an intrinsic viscosity of 2-6d6/g or less, provided that the sum of A), (+31 and (0) is 10% by weight)
The present invention provides a polypropylene composition having excellent low-temperature impact properties and impact whitening resistance.

In the polypropylene composition of the present invention, component (A) is polypropylene having an isotactic index of 89 or more. The isotactic index is A for homopolypropylene, J2 by Zambell-j et al. is MaQrOmO]
This is the isotactic fraction of the methyl group in triat units according to the C-NMR method published in , eQulθg6, 925 (1973). The polypropylene random copolymer was also prepared in accordance with the method of A., Zamlj, et al., taking into consideration the influence of comonomers.

The polypropylene is a propylene homopolymer or a copolymer of propylene containing 95 mol % or more of propylene and ethylene or other α-olefin. Component (A) accounts for 46 to 64 weight percent, preferably 50 to 59 weight percent, of the composition of the present invention. Component (B) consists of ethylene and propylene having an average content of propylene units of 40 to 85 mole percent. The random copolymer is preferably substantially amorphous. Component (B) accounts for 1 to 7% by weight, preferably 6 to 5% by weight, in the composition of the present invention.

If the amount of component (B) is less than 1% by weight, the impact strength will be low;
If it exceeds % by weight, the resistance to RL&'JH whitening is poor.

Component (0) is polyethylene having an intrinsic viscosity of 2-6 de/g or less, preferably 1.8 to 2.3 de/g. If the intrinsic viscosity exceeds 2-6 dl/g'f, the gloss of the composition will be reduced. The intrinsic viscosity is decalin solvent 13
This is a value measured at 5°C. Furthermore, polyethylene as used in the present invention refers not only to a homopolymer of ethylene but also to a copolymer of ethylene and other α-olefins having an average content of ethylene units of 93 mol% or more, preferably 97 mol% or more. It is a highly crystalline polymer. and component (a)
occupies in the composition of the present invention an amount of 66 to 50 weight ft.
%, preferably 68 to 45 times ff1%. If the amount of component (C) is less than 36% by weight, the impact strength will not be sufficient, and if it exceeds 50% by weight, the stiffness and heat distortion temperature will be significantly lowered.

Next, a method for producing a polypropylene composition comprising components (A), (B) and (0) of the present invention will be explained. The composition of the present invention can be prepared by mechanically mixing the components that have been polymerized separately in advance, or by polymerizing the olefins in one polymerization reaction system in the presence of a stereoregular catalyst, and then uniformly mixing the components. It can be obtained by a method of mixing different methods or a method of combining these methods.

To obtain the composition of the present invention by mechanically mixing each component,
It is necessary to pay sufficient attention to ensure that each component does not cause poor dispersion. Examples of the melt kneader used for mixing include a Banbury mixer, a Nigu, a twin-screw extruder, and a double-screw extruder. The order of mechanical mixing is not particularly limited, but the first step is to mix components (B) and (0
) is preferably kneaded, and then the kneaded product and component (A) are kneaded because a composition with a good balance between impact resistance and rigidity can be obtained with good reproducibility.

Polymerizing olefins in one polymerization reaction system means
Refers to the preparation of a polymer mixture by sequentially producing components (A), (B) and ((11) in one or more reactors, usually components (A), (B) and The catalyst is not deactivated in the cold to produce (0). Components (A), (E), and (0) can be produced in any order, but in particular, components (A), (B)
It is preferable for the polymerization operation to produce and (0) in this order, and is suitable for industrial production.

The stereoregular catalyst used in the production of each component of the polymer composition of the present invention is usually a catalyst used in the production of crystalline polypropylene. A typical example is a transition metal catalyst component such as a supported transition metal component in which titanium trichloride or a transition metal compound is supported on a carrier, and an alkyl aluminum compound or its halogen compound, hydride, or alkoxide. or a six-component catalyst system in which an organic compound containing nitrogen, phosphorus, sulfur, oxygen, silicon, boron, etc. is added to the two-component catalyst system.

As the titanium trichloride catalyst component, titanium tetrachloride can be reduced by various known methods, and the titanium trichloride produced can be activated by ball milling or solvent washing (washing with an inert solvent or an inert solvent containing a polar compound). You can use the converted version.

As the supported titanium catalyst component supported on a carrier, a catalyst component in which a transition metal compound is supported on an inert solid carrier is used. Examples of transition metals include titanium and vanadium, but titanium is particularly preferred for components (A>, (B) and (0)).

Among the supported titanium catalyst components, those containing at least magnesium, halogen, and titanium on the surface of the supported titanium catalyst component, or those containing these and an electron donor are preferably used. Of course, there is no problem in containing elements other than these. As the inert solid carrier, various magnesium compounds are preferably used, and magnesium halides are particularly preferably used. For example, as the carrier material titanium catalyst component, a titanium composite whose main components are a magnesium halogen compound, a titanium halogen compound, and an organic carboxylic acid ester is preferably used.

As the above-mentioned supported titanium catalyst component used in the present invention, for example, the conventionally proposed JP-A-50-10838
No. 5, JP-A-50-126590, JP-A-48-16
It is possible to use a carrier-mounted titanium catalyst component disclosed in Japanese Patent Application No. 986, which contains magnesium and halo-f-7 on the surface thereof, and a carrier-mounted titanium catalyst component which contains these and an electron donor.

Specific methods for polymerizing components (A), (B), and (C) in the present invention in one polymerization reaction system include JP-A No. 52-98045 and JP-A No. 53-98, filed by the present applicant.
Learn more about issue 88049.

In addition, polyethylene which is component (0) in the present invention or ethylene/α- containing 7 mol% or less of α-olefin
As the olefin copolymer, those polymerized using a known Ziegler catalyst can also be used.

When preparing the composition of the present invention, various additives such as antioxidants, ultraviolet absorbers, lubricants, nucleating agents, antistatic agents, flame retardants, pigments, dyes, inorganic or organic fillers, etc. may be added at any stage of the mixing thereof. Additives may be added within a range that does not impair the purpose of the present invention.

Molded products using the polypropylene composition of the present invention have excellent low-temperature impact resistance, impact whitening resistance, and gloss, and are also rigid, so they can be used for automotive parts such as battery cases, trim panels, and washing machine top panels. , suitable for home appliance parts such as vacuum cleaner housings.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these embodiments unless they go beyond the gist of the invention.

Example 1 [Preparation of titanium catalyst component] Anhydrous magnesium chloride, ethyl benzoate, and methylpolysiloxane were contacted in a stainless steel vibrating ball mill cylinder containing a stainless steel pole in a nitrogen atmosphere to obtain a solid treated product. was suspended in titanium tetrachloride, washed with purified hexane, and dried to obtain a titanium-containing solid catalyst component. The components include 2.0% by weight of titanium on an atomic basis;
It contained 65.0% by weight of chlorine and 8.0% by weight of ethyl benzoate.

[Production of a polymer composition consisting of components (A), (B) and (0)] Using the above titanium catalyst component and a catalyst consisting of triethylaluminum and p-)methyl ruylate, three polymerization vessels are connected in series. Using a device consisting of a flash tank H installed between E, F, G and polymerization vessels F and 0,
Melt index (hereinafter abbreviated as MI) in polymerizer A
STM D 12613]L) 11-5 g7
10 m1n-.

Isotactic index (hereinafter abbreviated as EE) 96% (01
3NMR method) polypropylene (A) was obtained. Next, ethylene and propylene were copolymerized in polymerization vessel F.

Next, after passing through a flash tank H, ethylene was polymerized in a polymerization vessel G to obtain MI5.9 g710 ml, component (A) of n.
, (B) and (0) was obtained. The intrinsic viscosity of polyethylene (0) produced in polymerization vessel G is
2.246.17g and 38% for the polymer composition
The proportion of propylene units in the ethylene-propylene random copolymer (B) produced in polymerization vessel F was 50 mol%, which was 4% by weight based on the polymer composition.

An antioxidant was added to the polymer composition (1), and a 3-ounce injection molding machine was used at a resin temperature of 240°C and an injection pressure of 100°C.
0 kg10n2a, injection time 10 seconds, length 13D
The sample was injected into a mold having a width of 120 mm and a thickness of 2.0 mm to prepare a test piece for measuring the following properties.

Gloss (Q4osJ: According to ASTM D 523.

Incident angle 20°.

Initial flexural modulus (FM) + According to ASTM D 790.

Falling strength (FD) A weight of a certain shape is dropped from a certain height onto a horizontally placed test piece at a temperature of 10°C, and by varying the weight of the weight, the test piece is measured until 50% of a certain number of test pieces break. Impact strength (kg-On
) was sought.

Whitening degree: test piece (12X 13c1〃) is 1ox1oa
The edges are fixed to form an n-angle, and a 500 g steel ball is dropped onto the center from a height of 10 DCIn to cause impact whitening. It was classified into three ranks based on the density of the whitening and its diameter.

A: Almost no change.

B: A pale white pattern with a diameter of about 1.5 mm is produced.

C: A white pattern with a diameter of about 2 to 3 m is produced.

The results are shown in Table 1.

12-Example 2 MI: 12.3 g/1 in the same manner as Example 1
[] mi, n, 1 engineering: 95.5% polypropylene (
A), a polymer composition (11
): MI 5.8g710m1n (polyethylene (C) fl: 40% by weight, amount of ethylene-propylene copolymer (B): 3% by weight) was obtained. A test piece was prepared in the same manner as in Example 1, and its physical properties were measured. The results are shown in Table 1.

Comparative Example 1 MI: 11-6 g/I by the same method as Example 1
C] Min%: A polymer consisting of 96% polypropylene (A), polyethylene (C) with an intrinsic viscosity of 2.5'Od1/g, and propylene units: 65 mol% ethylene/propylene random copolymer (B) Composition (Ill):
MI;'8 (1/I Dmi,n [amount of polyethylene (C): 20% by weight, amount of ethylene-propylene random copolymer CB): 4% by weight) was obtained.

Thereafter, test pieces were prepared in the same manner as in Example 1, and their physical properties were measured. The results are shown in Table 1.

Example 3.4 and Comparative Example 2.3 Anhydrous magnesium chloride, ethyl benzoate and methylpolysiloxane 'f:'! After grinding with M moving ball mill,
MI: 15 g/I Qmin, II using a catalyst consisting of a titanium catalyst component having a titanium content of 1.9% by weight and a chlorine content of 65% by reaction with titanium tetrachloride, triethylaluminum and methyl p-)ruylate. :96%
Polypropylene (A) was obtained.

On the other hand, random copolymerization of propylene and ethylene was carried out using the titanium catalyst component and a catalyst consisting of triethylaluminum and ethyl benzoate, and propylene-containing ft.
6omol% ethylene/propylene random copolymer (
B) was obtained.

Density of the polymerized ethylene-propylene copolymer (E) and Ziegler catalyst: 0.9628/ffζ[η
]: Add an antioxidant to 2.02 dff/g polyethylene (C) and mix with a Henschel mixer in the proportions shown in Table 1. After kneading and granulating with a 65 mmφ single screw extruder (resin temperature 210 ° G), This kneaded product and the polypropylene (A)
All of the antioxidants were added to the mixture and mixed in the ratio shown in Table 1 using a Henschel mixer, followed by kneading and granulation using the extruder.

Claims (1)

[Claims] (1) (A) 46 to 64 mol% of polypropylene with an isotactic index of 89 or more, (B) 1 to 7 mol% of ethylene/propylene random copolymer containing 40 to 85 mol% of propylene units, and (C) Polyethylene 36 with an intrinsic viscosity of 2-6 dl/g or less
or 50% by weight, provided that the total amount of A), (B) and (0) is 100% by weight
A polypropylene composition consisting of: