JPS62151446A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE:The titled resin composition having high stiffness modulus and improved low-temperature impact resistance, obtained by blending a specific propylene-ethylene block copolymer with two specified amorphous etylene.alpha- olefin copolymers and talc. CONSTITUTION:(A)60-80wt% crystalline propylene-ethylele block copolymer having 15-50g/10min melt flow index and 5-10wt% ethylene content is blended with (B) 5-15pts.wt. amorphous etylene.alpha-olefin (preferably propylene) copolymer having 5-30 Mooney viscosity and 70-90 hardness of JIS-A of raw rubber, (C) 15-35pts.wt. amorphous ethylene.alpha-olefin (preferably propylene) having 50-70 Mooney viscosity and 50-70 hardness of JIS-A and (D) 10-20pts.wt. based on 100pts.wt. total amounts of the components A, B and C of talc having preferably 0.5-5mum average particle diameter to give the aimed composition.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a polypropylene resin composition having a high flexural modulus and excellent low-temperature impact resistance. More specifically,
By using a crystalline propylene-ethylene block copolymer, an amorphous ethylene-propylene copolymer, and talc in a specific ratio, the present invention has a high flexural modulus, excellent low-temperature impact resistance, and silomole. The present invention relates to a polypropylene composition suitable as an injection molding material for automotive exterior products such as Pan/Q-, Bumper Corner, etc.

<Prior Art> Crystalline polypropylene resins are widely manufactured and used industrially. Crystallinity, f Lipropylene tree has high flexural modulus, excellent impact resistance at room temperature, and is relatively inexpensive.
Widely used for interior and exterior parts of automobiles, parts for home appliances, etc.

However, crystalline polypropylene resin has a drawback of poor impact resistance at low temperatures such as 0°C or lower. As a means to improve the impact resistance of this polypropylene resin at low temperatures, it is possible to randomly or block copolymerize propylene with ethylene or an α-olefin monomer other than propylene, or to add an amorphous ethylene-propylene copolymer to the polypropylene resin. Measures such as blending are being taken.

However, in order to obtain impact resistance at extremely low temperatures such as -30'C required for automobile parts, it is necessary to increase the copolymerization ratio of α-olefin other than ethylene or propylene in the above copolymerization. In blending, it is necessary to increase the blend r ratio of the amorphous ethylene-propylene copolymer, which results in the disadvantage of impairing the flexural modulus, which is an inherent advantage of crystalline polypropylene resins. As a method to maintain the high flexural modulus that is an advantage of crystalline polypropylene resin and to improve impact resistance at low temperatures, we added an amorphous ethylene-propylene copolymer to a specific crystalline propylene-ethylene copolymer. Used together,
Furthermore, inorganic fillers such as talc are also used in combination.

However, commercially available crystallinity, )? A composition in which IJ propylene resin is blended with talc and an amorphous ethylene/α-olefin copolymer, which has the low hardness of raw rubber, has improved impact resistance at low temperatures, but has a large flexural modulus. descend. This tendency is particularly noticeable when using an ethylene/α-olefin copolymer with a high Mooney viscosity.

On the other hand, when an ethylene/α-olefin copolymer having high raw rubber hardness is blended, there is a problem in that although there is little decrease in bending elasticity, there is also little effect on improving impact resistance at low temperatures.

<Disclosure of the Invention> In order to obtain a polypropylene resin composition that has both a high flexural modulus and excellent low-temperature impact resistance, the present inventors
As a result of intensive research, we have achieved this goal by a specific combination of a specific crystalline progylene/ethylene block copolymer, two or more types of amorphous ethylene/α-olefin copolymers, and talc. Successful.

That is, the present invention provides (a) a melt flow rate of 15 to
50.9/10 min crystalline propylene-ethylene block copolymer ω ~ closed weight parts, (b) Mooney viscosity 5-30
Raw rubber J Engineering S-A Amorphous ethylene with hardness of 70 to 90.
α-olefin copolymer 5-15 parts by weight, (c) Mooney viscosity 50-70, raw rubber J-S-A hardness 50-70
Amorphous ethylene/α-olefin copolymer 15-35
Parts by weight (however, the total of parts by weight of the above (a), (b), and (c) is 100 parts by weight) and 10 to 20 parts by weight of talc
The present invention provides a noripropylene resin composition consisting of 1 part.

The melt flow rate of the crystalline propylene/ethylene copolymer (a) used in the present invention is 15 to 50 F.
The range is 710 minutes, and the ethylene content is 5 to 10 minutes.
It is about the weight level. In this case, if the melt flow rate is less than 15, the fluidity of the composition will decrease and it will not be suitable for large molded products, and the melt flow rate will still be less than 50.
If it exceeds the above range, physical properties such as impact resistance and tensile elongation will be poor, so it is not preferable.

The above amorphous ethylene (b) used in the present invention.

The α-olefin copolymer has a Mooney viscosity (M
Ll+4 (100'C)) is 5 to 30, raw rubber J
The S-A hardness is 70 to 90. Examples of α-olefins in this amorphous ethylene/α-olefin copolymer include propylene, butene-1, and pentene-1.
1, hexene-1, etc. A preferred α-olefin is propylene.

If the amorphous ethylene/α-olefin copolymer in (b) above has a Mooney viscosity of less than 5, sufficient improvement in physical properties such as impact resistance cannot be obtained, and if the Mooney viscosity exceeds that of a sword. In other words, it reduces the fluidity of the composition.

If the raw rubber hardness (JIS-A) of the amorphous ethylene/α-olefin copolymer in (b) above is less than 70, the flexural modulus of the composition decreases, and if it exceeds (g). In this case, the effect of improving impact resistance cannot be sufficiently obtained.

Examples of the α-olefin in the amorphous ethylene/α-olefin copolymer (c) above include haflopyrene,
Examples include phthene-1, hanten-1, and hexene-1. The preferred α-olefin is haflopyrene.

The Mooney viscosity (MLl+4 (100°C)) of the amorphous ethylene/α-olefin copolymer (c) above is 50
~70. If the Mooney viscosity is less than I, the impact resistance and tensile elongation will be poor, and if it exceeds 70, the fluidity of the composition will be reduced.

The hardness of the raw rubber of the amorphous ethylene/α-olefin copolymer (JIS-A) in (c) above is 50 to 70, and if it is less than 70, the flexural modulus of the composition will be low, and the hardness will be lower than 70. If it exceeds the above range, the effect of improving impact resistance cannot be sufficiently obtained.

The talc used in the composition of the present invention is generally commercially available. Preferably, the average particle diameter is 0.
It is 5 to 5 μm. There is a tendency for impact resistance to decrease as the particle size of talc increases.

The usage ratios of each copolymer (a), (b), and (c) above are (a) crystalline propylene/ethylene block copolymer, (b) amorphous ethylene/α-olefin copolymer, and (c) ) Considering the total weight of the amorphous ethylene/α-olefin copolymer as 100 weight parts, (a) 60 to 80 parts by weight, (b) 5 to 15 parts by weight, (c) 15 to 35 parts by weight, and The amount of talc is in the range of 10 to 20 parts by weight.

If the proportion of the crystalline ethylene/zolopyrene block copolymer in (a) above is less than part by weight, the flexural modulus will be low, and if it exceeds 80 parts by weight, the impact resistance at low temperatures will decrease. It becomes inferior.

If the content of the amorphous ethylene/α-olefin copolymer in (b) above is less than 5 parts by weight, the fluidity of the composition will decrease, while if it exceeds 15 parts by weight, the tensile elongation will be low. Become something.

If the amount of the amorphous ethylene/α-olefin copolymer in (c) above is less than 15 parts by weight, the impact resistance at low temperatures will be poor, and if it exceeds 3 parts by weight, the flexural modulus will be low. Become something.

Regarding the usage ratio of the amorphous ethylene/α-olefin copolymer in (b) above and the copolymer in (c) above, the weight part in (c) of (b) is taken as Zoo. If it exceeds Koma, the impact resistance at low temperatures will be low, and the tensile elongation will also be poor, which is not preferable.

If the amount of talc used is less than 10 parts by weight, the bending elastic modulus will be low, and if it exceeds the weighted bone portion, the impact resistance will be poor.

According to the present invention. (d) To the polypropylene resin composition, auxiliary additive components commonly used in this field, such as oxidation inhibitors, heat stabilizers, light stabilizers, ultraviolet absorbers, pigments, lubricants, etc., can be added.

Preparation of the compositions of the invention (in general, each t!
A closed-type mixer such as a single-screw extruder or multi-screw extruder used for blending Li resin, or a Banbury mixer 1 pressurized kneader is used.

The composition of the present invention includes a specific crystalline propylene/ethylene block copolymer, a specific amorphous ethylene block copolymer, and a specific amorphous ethylene block copolymer.
By using two types of α-olefin copolymers and talc in specific proportions, it has a high flexural modulus, excellent impact resistance at low temperatures, and has exceptional fluidity. It is particularly suitable for automotive exterior parts such as pans, e-coats, bumper corners, and side moldings.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited by the following Examples.

Examples 1 to 8 Depending on the composition of each copolymer component and other raw material components shown in Table 1, each component was placed on each side in a 16 Kisuno e-mixer manufactured by Kawaguchi Seisakusho and heated for 3 minutes. mix,
A mixture was prepared by mixing to a homogeneous state.

Each mixture was passed through a 30 mm diameter twin-screw extruder manufactured by Nakayo Kikai Co., Ltd. to form cylindrical pellets. The extrusion conditions are as follows.

Temperature ('C) Ox 02 C
3c4 Gui temperature (C) 220 Number of revolutions per screw (rpm) 80 Using cylindrical tablets blended in a two-screw extruder, test pieces were made in a Z injection molding machine in step 5 under the injection molding conditions below, and various properties were evaluated. I did it.

Injection molding conditions Niji cylinder temperature 1 tres (℃) C2C3 nozzle temperature ('C) 210 Injection pressure (kgf/crIL'') 800 Mold temperature ('C) 45 Test piece cleaning and melt flow rate of each example ,
Flexural modulus, -30℃ isot impact strength (notched)
, test for tensile strength and tensile elongation: nSK 6
Table 1 shows the results obtained in accordance with 758.

Comparative Examples 1 to 8 Using the formulations of each copolymer component and other raw material components shown in Table 2, granulation molding for test piece production and test piece evaluation were performed in the same manner as in the above example. . The results are shown in Table 2.

From the results in Tables 1 and 2, the following is clear.

Comparative Example 1.2 KPM (U-a) and gpM (n-b
) is used alone, but EPM (rr-a)
The impact resistance of Comparative Example 1 using EPM (I
The flexural modulus of Comparative Example 2 using I-b) is inferior to that of the Example.

Comparative Example 3 is an example in which 'gpM (III), which has a low Mooney viscosity and low raw rubber hardness, is used instead of KPM ([-b). The flexural modulus of the obtained product is on the same level as that of the example, but the impact resistance is inferior to that of the example.

Comparative Example 4 uses EPM instead of FiPM (II-a)
This is an example when (■) is used. The flexural modulus of this example is inferior to that of the example.

Comparative Examples 5 and 6 are examples in which the amount of PP used was changed. Comparative Example 5, which uses a large amount of PP, has an impact resistance, and Comparative Example 6, which uses a small amount of PP, has a flexural modulus that is inferior to that of the Examples.

Comparative Examples 7 and 8 are examples in which the amount of talc used was changed. Comparative Example 7, in which a small amount of talc was used, had a flexural modulus, and Comparative Example 8, in which a large amount of talc was used, had an impact resistance that was inferior to that of the Examples.

Claims (1)

[Claims] 1. (a) 60 to 80 parts by weight of a crystalline propylene-ethylene block copolymer with a melt flow rate of 15 to 50;
(b) Mooney viscosity 5-30, amorphous ethylene/α-olefin copolymer with raw rubber JIS-A hardness 70-90 5-15 parts by weight, (c) Mooney viscosity 50-70, JI
15 to 35 parts by weight of an amorphous ethylene/α-olefin copolymer with an S-A hardness of 50 to 70 (however, the above (a), (
A polypropylene resin composition comprising 10 to 20 parts by weight of talc (with the total weight parts of b) and (c) being 100 parts by weight). 2. The polypropylene resin composition according to claim 1, wherein the talc has an average particle size of 0.5 to 5 μm. 3. Claim No. 3, wherein the amorphous ethylene/α-olefin copolymer of (b) and the amorphous ethylene/α-olefin copolymer of (c) are amorphous ethylene/propylene copolymers. The polypropylene resin composition according to item 1.