JP3331009B2 - Polypropylene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition which is excellent in impact resistance and rigidity and is suitable for use as a material for automobile bumpers and automobile interior / exterior parts.

[0002]

2. Description of the Related Art As materials for bumpers and interior / exterior parts of automobiles, blend polymers of polypropylene and ethylene-propylene rubber such as propylene homopolymer, propylene block copolymer and propylene random copolymer, and polypropylene and For example, a blend polymer of ethylene-propylene rubber and ethylene-butene rubber is used.

[0003] However, a material comprising a blend polymer of polypropylene and ethylene-propylene rubber has a disadvantage that the impact resistance is sufficient but the elongation and rigidity are not sufficient. On the other hand, polypropylene, ethylene-propylene rubber and ethylene -With a material comprising a blend polymer with butene rubber, elongation and rigidity are improved, but there is a phenomenon that impact resistance at low temperatures is not sufficient.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polypropylene resin composition which is excellent in impact resistance, elongation, and rigidity and is suitable for automobile bumpers and the like.

[0005]

The object of the present invention is to provide (A) 60 to 80 parts by weight of polypropylene, (B) 10 to 30 parts by weight of ethylene-propylene rubber, and (C) polyethylene-ethylene / butene-polyethylene triblock copolymer. Coalescing 1
(B) ethylene-propylene rubber having a propylene content of 15 to 50% by weight, an intrinsic viscosity of 1.5 to 7.0 dl / g, and (C) a polyethylene-ethylene rubber. / The content of the polyethylene block of the butene-polyethylene triblock copolymer is 30 to
70% by weight, the content of butene in the ethylene / butene block is 30 to 80% by weight, (A) a rubber component of polypropylene, (B) ethylene-propylene rubber, and (C) polyethylene-ethylene / butene- The problem is solved by a resin composition having a total amount of 20 to 50% by weight of the total composition with the polyethylene triblock copolymer.

Hereinafter, the present invention will be described in detail. As the polypropylene (A) in the resin composition of the present invention, a propylene homopolymer (homopolypropylene);
Any of a block copolymer and a random copolymer,
Alternatively, two or more of these can be used in combination. As the comonomer of the block and random copolymer, α-olefins other than propylene such as ethylene, butene-1, pentene-1, and hexene-1 are used, and among them, ethylene is particularly preferable. The propylene content in these copolymers is in the range of 80-100 mol%. A random copolymer is obtained by polymerizing a mixed gas of propylene and another α-olefin, while a block copolymer is obtained by first polymerizing propylene and then propylene and another α-olefin. What was obtained by copolymerizing with is used.
In the block copolymer using ethylene as the α-olefin, the ethylene-propylene block in the molecule is dispersed in the homopolypropylene block to exhibit rubber elasticity, and functions as a rubber component. The content of the rubber component is preferably 10 to 20% by weight of the block copolymer.

[0007] The melt flow index (MFR) of these polypropylenes (A) is 5 to 1 at a temperature of 230 ° C.
It is preferably in the range of 00 g / 10 minutes. If the MFR is less than 5 g / 10 minutes, the fluidity of the obtained resin composition is poor, and the moldability is deteriorated. If the MFR exceeds 100 g / 10 minutes, the impact resistance of the resin composition will be poor. These polypropylenes may be those having a low MFR, kneaded with an organic peroxide, and subjected to bisbreaking, so that the MFR is within the above range.

The ethylene-propylene rubber (B) used in the present invention has a propylene content of 15%.
To 50% by weight. If the propylene content is less than 15% by weight, the affinity and compatibility with the polypropylene (A) are deteriorated, and mechanical properties such as impact resistance are reduced. On the other hand, when the propylene content exceeds 50% by weight, the handleability of the resin composition deteriorates. The ethylene-propylene rubber (B) has an intrinsic viscosity [η] of 1.5 to 7.0 d.
Those having a range of 1 / g are selected. 1.5 dl intrinsic viscosity
/ G, the impact resistance of the obtained resin composition decreases, and if it exceeds 7.0 dl / g, the dispersibility of the ethylene-propylene rubber (B) in the resin composition decreases, and The impact resistance of the object is reduced, which is inconvenient.

In the resin composition of the present invention, the third component (C) polyethylene-ethylene / butene-polyethylene triblock copolymer (hereinafter abbreviated as triblock copolymer) has ethylene at the center of the molecule. / Butene copolymer block, and polyethylene blocks on both sides of the copolymer block. The total content of the polyethylene blocks in the triblock copolymer (C) is 30 to 70% by weight in the triblock copolymer. If the amount is less than 30% by weight, the rigidity of the obtained resin composition decreases, and if it exceeds 70% by weight, the low-temperature impact resistance of the resin composition decreases, which is disadvantageous.

The content of butene in the ethylene / butene block located at the center of the triblock copolymer (C) is in the range of 30 to 80% by weight. If the content of this butene is less than 30% by weight, the compatibility between the (C) triblock copolymer and (A) polypropylene will be reduced, and the impact resistance will be reduced. Is inconvenient because of its reduced heat resistance. Tribs like this
As a method for producing the lock copolymer (C), for example,
M. Morton "Thermoplastic El
astromer "N. R. Legge, G .; Holde
n, H .; E. FIG. Schroeder Edition Hanser P
ulishers (1987), page 87.
Butadiene using an organolithium compound as a catalyst
Polymerizes a triblock polymer using only
Polybuta 1.4-structure with 90% or more terminal blocks
It is a diene and the central block is about 45% 1.2-structure
A polybutadiene polymer, and the polymer
In the solution, and lightly branch the blocks at both ends.
Crystalline polyethylene, and the center block is
The method of making a random copolymer of styrene and butene-1
No. Both triblocks used in the examples described later
The polymer was synthesized by this method.

Further, the mixing ratio of each component in the resin composition of the present invention is based on 100 parts by weight of the whole resin composition.
(A) Polypropylene is 60 to 80 parts by weight.
(A) If the amount of polypropylene is less than 60 parts by weight, heat resistance is not sufficient, and if it exceeds 80 parts by weight, impact resistance is reduced. On the other hand, the content of (B) the ethylene-propylene rubber is 10 to 30 parts by weight per 100 parts by weight of the resin composition. When the content of the ethylene-propylene rubber is less than 10 parts by weight per 100 parts by weight of the resin composition, the obtained composition has low impact resistance at low temperatures. Also, 3
If it exceeds 0 parts by weight, heat resistance will be reduced.

Further, the content of (C) the triblock copolymer is 10 to 30 parts by weight per 100 parts by weight of the resin composition. Resin composition 1 containing triblock copolymer
If the amount is less than 10 parts by weight per 100 parts by weight, the elongation to failure of the obtained composition is reduced. If the amount exceeds 30 parts by weight, heat resistance and impact resistance at low temperatures are reduced. The total amount of the rubber component (A) in the polypropylene, the ethylene-propylene rubber (B) and the triblock copolymer (C) is 20 to 50% by weight of the whole resin composition. is there. If the content of all rubber components is less than 20% by weight of the whole resin composition, the impact resistance of the obtained composition will be reduced. Also, 50
If the amount is more than 10% by weight, the heat resistance of the obtained composition is reduced.

The compounding method (mixing method) for obtaining the resin composition of the present invention is not particularly limited, and a method generally used in the field of synthetic resins may be applied.
As a mixing method, a method of dry blending using a mixer such as a Henschel mixer, a tumbler and a ribbon mixer, which is generally performed, and melting while using a mixer such as an open roll, an extruder, a kneader and a Banbury are used. There is a method of mixing. Among these methods, in order to obtain a more uniform composition, two or more of these mixing methods may be used in combination (for example, after dry-blending in advance, then melt-mixing the mixture). Regardless of the case where they are used in combination, or the case where one or two or more methods of melt-mixing are used in combination, it is preferable to produce pellets using a pelletizer and use them when producing a molded article by the molding method described below.

In addition, in the formulation of the resin composition of the present invention, heat, oxygen and light stabilizers, flame retardants, fillers, coloring agents, lubricants, plasticizers widely used in the field of polypropylene resin compositions. Further, an additive such as an antistatic agent may be added within a range that does not essentially impair the properties of the composition of the present invention, depending on the intended use of the composition. Of the above mixing methods, even when melt mixing,
Even in the case of molding by the molding method described later, the molding must be performed at a temperature at which the polymer substance used melts.
However, if carried out at a high temperature, the polymer material will undergo thermal decomposition and degradation. From these, generally 180-
It is carried out at 300C, preferably at 200 to 280C.

The polypropylene resin composition of the present invention comprises:
A molding method such as an injection molding method, an extrusion molding method, a compression molding method, and a hollow molding method generally used in the field of synthetic resins may be applied to form a desired shape. Further, after forming into a sheet using an extruder, the sheet may be formed into a desired shape by a secondary processing method such as a vacuum forming method or a pressure forming method.

Hereinafter, the operation and effect will be clarified by showing specific examples. In the following examples, the IZOD impact strength (kg-
cm / cm) was measured at −30 degrees according to ASTM D265. Flexural modulus (kg / cm ² )
It was measured based on STM D790. Tensile elongation (%) was measured at room temperature based on ASTM D638. [A] Polypropylene The polypropylene (referred to as PP) used in the present invention is a block type polypropylene M manufactured by Showa Denko KK
K711 (PP-1), homopolypropylene MA810
B (PP-2) was used. The MFR at 230 ° C. is 40 g / 10 min and 30 g / 10 min, respectively, and the rubber content is 15% by weight and 0% by weight, respectively.

[B] Ethylene-propylene rubber The intrinsic viscosity [η] and propylene content (% by weight: F) of the ethylene-propylene rubber (referred to as EPR) used in the present invention.
Called p. ) Is as follows.

[Table 1] [C] Triblock copolymer The following was used as the polyethylene-ethylene / butene-polyethylene triblock copolymer (hereinafter referred to as TBC) used in the present invention.

[Table 2]

For comparison, instead of the triblock copolymer (TBC), ethylene / butene rubber (intrinsic viscosity [η] = 3.5 d1 / g, butene content 15% by weight, EB
Notated as R. ) Was used. These components were blended according to the composition shown in Table 1, kneaded with a co-rotating twin-screw extruder to produce pellets, and then specimens were prepared with an injection molding machine. The IZOD impact strength, flexural modulus and tensile elongation of the obtained test piece were measured. The results are shown in Table 1. The PP of Example 3 in Table 1 is P
35 parts by weight of P-1 and 35 parts by weight of PP-2 are used in combination.

[0019]

[Table 3]

From the results in Table 3, (A) polypropylene,
According to the resin composition of the present invention in which (B) the ethylene-propylene rubber and (C) the triblock copolymer are combined, it is found that a resin excellent in impact resistance, rigidity and tensile elongation can be obtained. On the other hand, the combination of polypropylene and ethylene-propylene rubber has good impact resistance but insufficient elongation, while the combination of polypropylene and ethylene-butene rubber has good elongation but insufficient impact resistance. You can see that

[0021]

As described above, the polypropylene resin composition of the present invention comprises (A) polypropylene, (B)
Ethylene-propylene rubber and (C) polyethylene-
Since it is a combination of ethylene / butene-polyethylene triblock copolymer, both impact resistance, elongation, and rigidity are excellent, and the balance is obtained.
It is suitable as a material for automobile bumpers and interior / exterior parts.

────────────────────────────────────────────────── ─── Continued on the front page Examiner Takeshi Sato (56) References JP-A-5-345845 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 23/04-23 / 16 C08L 53/00-53/02

Claims (1)

(57) [Claims] (1) 60 to 80 parts by weight of a polypropylene, (B) 10 to 30 parts by weight of an ethylene-propylene rubber, and (C) 10 to 30 parts by weight of a polyethylene-ethylene / butene-polyethylene triblock copolymer. (B) The ethylene-propylene rubber has a propylene content of 15 to 50% by weight and an intrinsic viscosity of 1.5 to 7%.
0 dl / g, (C) the polyethylene-ethylene / butene-polyethylene triblock copolymer has a polyethylene block content of 30 to 70% by weight, and the ethylene / butene block has a butene content of 30 to 80% by weight. (A) a rubber component of polypropylene, and (B) ethylene-
A polypropylene-based resin composition, wherein the total amount of propylene rubber and (C) polyethylene-ethylene / butene-polyethylene triblock copolymer is 20 to 50% by weight of the whole composition.