JPH08302095A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE: To obtain a polypropylene resin composition high in rigidity and low temperature impact resistance by compounding polypropylene with an ethylene/α-olefin structure elastomer (e.g. ethylene/propylene copolymer elastomer) wherein an L value defined by a specific equation on the sweep- measurement of temperature on the measurement of dynamic viscoelasticity exhibits a specific value. CONSTITUTION: (A) 50-95wt.% of polypropylene and (B) 5-50wt.% of an ethylene/α-olefin structure elastomer (e.g. ethylene/propylene copolymer elastomer) having a L value expressed by the equation in a value of 15-100 on the sweep measurement of temperatures on the measurement of the dynamic viscoelasticity are compounded with each other, dry-blended by the use of a Henschel mixer for 5min, and subsequently kneaded with a biaxial extruder disposed in the same direction at 210 deg.C. The produced pellets are molded with an injection molding machine set at 230 deg.C to obtain the objective polypropylene resin composition containing the component B and the rubber component contained in the component A in a total amount of 5-50wt.%, having high rigidity and excellent low temperature impact resistance, and useful as a raw material used for industrial members, etc.

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 having high rigidity and excellent low temperature impact resistance, which is suitable as a material for industrial members.

[0002]

2. Description of the Related Art Conventionally, as a technique for improving the impact resistance of polypropylene resins such as propylene homopolymer, propylene block copolymer, and propylene random copolymer, a blend polymer of ethylene / propylene copolymer ( JP-B-60-3420) and blend polymers of ethylene / propylene copolymer and ethylene / butene copolymer (JP-A-4-372637) are known.

However, a material composed of a blend polymer of polypropylene and an ethylene / propylene copolymer,
A material composed of a blend polymer of polypropylene, an ethylene / propylene copolymer, and an ethylene / butene copolymer has improved rigidity and impact resistance at room temperature, but has a temperature of about −30 ° C. required as an industrial member. It had the drawback of low impact resistance at low temperatures.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polypropylene resin composition having high rigidity and excellent low temperature impact resistance, and having an excellent balance of physical properties.

[0005]

[Means for Solving the Problems] The above problems are as follows: (A): 50 to 95% by weight of polypropylene, (B): temperature sweep measurement in dynamic viscoelasticity measurement,

[Equation 2] It is composed of 5 to 50% by weight of an ethylene / α-olefin structure elastomer having an L value represented by the formula (1) of 15 to 100, and the total of the rubber component and (B) contained in (A) is 5.
It can be solved by a polypropylene resin composition characterized by being ˜50% by weight.

(A) Polypropylene The polypropylene used in the present invention may be a propylene homopolymer, a block copolymer or a random copolymer, or a combination of two or more thereof. be able to. As the comonomer of the block and random copolymer, ethylene,
Although α-olefins other than propylene such as butene-1, pentene-1, and hexene-1 are used, ethylene is preferable among them. The propylene content in these copolymers is preferably 60 mol% or more, and particularly preferably 80 to 99 mol%. In the block copolymer using α-olefin as a comonomer, the ethylene / α-olefin 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 25% by weight of the block copolymer.

The melt flow rate of polypropylene in the present invention (measured in accordance with JIS K6758, hereinafter also referred to as MFR) is 1 to 100 g / 10.
Min is preferable, and 3 to 50 g / 10 min is particularly preferable. M
When the FR is less than 1 g / 10 minutes and more than 100 g / 10 minutes, the low temperature impact resistance of the obtained resin composition is lowered.

(B) Ethylene / α-olefin structure elastomer The ethylene / α-olefin structure elastomer is an elastomer having an ethylene / α-olefin structure, and includes ethylene / α-olefin copolymer and ethylene / α.
-A block copolymer having an olefin structure in a part of the molecule.

The ethylene / α-olefin structural elastomer is generally obtained by copolymerizing ethylene and α-olefin monomers. At this time, as α-olefin, propylene, butene-1, pentene-
1, hexene-1, heptene-1, octene-1 and the like, but propylene, butene-1, hexene-in terms of ease of production and good physical properties of the resulting material.
1, octene-1 are preferred.

The ethylene / α-olefin structure elastomer can also be obtained by hydrogenating a polymer obtained by using a diene such as butadiene or isoprene as a monomer. For example, an ethylene-ethylene / propylene block copolymer obtained by hydrogenating a copolymer having a 1,4-polybutadiene block and a polyisoprene block, 1,4-polybutadiene block and 1,2
-Ethylene-ethylene / butene block copolymer obtained by hydrogenating a copolymer having a polybutadiene / 1,4-polybutadiene block, and obtained by hydrogenating a copolymer having a polystyrene block and a polyisoprene block Styrene-ethylene / propylene block copolymers, polystyrene blocks and 1,2
Examples thereof include a styrene-ethylene / butene block copolymer obtained by hydrogenating polybutadiene in a copolymer having a polybutadiene / 1,4-polybutadiene block.

Ethylene / α-used in the present invention
The olefin structural elastomer has a frequency of 0.1 to 300 Hz and a heating rate of 0.1 to 10 in dynamic viscoelasticity measurement.
-150 to -3 when measured by temperature sweep at ° C / min
Value obtained by integrating the tan δ value with temperature within the range of 0 ° C. (Equation (1)
, And sometimes referred to as L value) is 15 to 1
00 is an ethylene / α-olefin structural elastomer.

(Equation 3)

The L value is an index showing the impact resistance of polymer materials, and the details of the theory are described in J. Appl. Poly. Sci., 11, 1661.
(1967) describes it by Wada et al. The tan δ value of the material at a certain frequency f ₀ is proportional to the energy dissipated when a shock wave corresponding to the frequency f ₀ is applied. Therefore, the temperature integrated value obtained by integrating tan δ from the absolute temperature of 0 ° C. to a certain temperature T ₀ is the frequency f ≧ f _{0 at the} temperature T ₀ .
It is proportional to the sum of the dissipated energy when a shock wave corresponding to all frequencies that satisfies is given. That is, the temperature integration value is proportional to the impact energy absorption of the material. Since the usual dynamic viscoelasticity measurement is performed by using liquid nitrogen to lower the temperature to about -150 ° C, it is desirable to use the value measured in the temperature range of -150 ° C or higher as an index. In general, a polymer material such as polyolefin has a tan δ value which is sufficiently small at −150 ° C. or lower because the molecular motion of the main chain is frozen. The present inventors have found that the L value is an index of impact energy absorption at −30 ° C., and the L value is extremely effective in designing an elastomer material used for improving low temperature impact resistance of a resin composition.

Ethylene / α-used in the present invention
L value of olefin structural elastomer is 15 to 10
It is 0, and 16 to 60 is preferable. When the L value is less than 15, the low temperature impact resistance of the obtained resin composition is lowered and the L value is 1
When it exceeds 00, the rigidity of the obtained resin composition decreases.
The ethylene / α-olefin structural elastomer having an L value of 15 or more can be obtained, for example, by setting the α-olefin content in the polymer to 40 to 80% by weight.

The MFR of the ethylene / α-olefin structure elastomer is preferably 0.5 to 100 g / 10 minutes, particularly preferably 1 to 50 g / 10 minutes. When the MFR is less than 0.5 g / 10 minutes or more than 100 g / 10 minutes, the low temperature impact resistance of the obtained resin composition is lowered.

(Composition ratio) The ratio of (A) in the polypropylene resin composition of the present invention is 50 to 95% by weight. If the proportion of (A) is less than 50% by weight, the rigidity will decrease, and if it exceeds 95% by weight, the low temperature impact resistance will decrease. The proportion of (B) in the polypropylene resin composition of the present invention is 1 to 50% by weight, 5 to 40% by weight.
Is preferred. When the composition ratio of (B) in the resin composition is less than 1% by weight, the low temperature impact resistance of the obtained polypropylene resin composition is lowered, and when it exceeds 50% by weight, the rigidity is lowered.

Further, the total amount of the rubber component contained in (A) and (B) in the polypropylene resin composition of the present invention (hereinafter sometimes referred to as total rubber amount) is 5 to 50.
% By weight. If the total amount of rubber in the resin composition is less than 5% by weight, the low temperature impact resistance of the obtained resin composition will decrease, and if it exceeds 50% by weight, the rigidity will decrease.

(Method for Producing Polypropylene Resin Composition) The polypropylene resin composition of the present invention contains a stabilizer for heat, oxygen, light, etc. and a crystal nucleating agent which are widely used in the field of synthetic resins and synthetic rubbers. , Lubricants, antistatic agents, flame retardants, fillers, colorants, plasticizers or polyethylene, poly 4-methyl-1-pentene, polystyrene, polybutadiene or styrene graft polymers of polyisoprene, polyester, polyamide, polycarbonate, etc. A molecular polymer or the like may be added at the time of producing a polypropylene resin composition or at the time of producing a molded product depending on the purpose of use.

The propylene resin composition of the present invention is (A)
The object can be achieved by uniformly blending (B) and the additive. The compounding method (mixing method) is not particularly limited, and a method generally used in the field of synthetic resins may be applied. As a mixing method, generally used is a method of dry blending using a mixer such as a Henschel mixer, a tumbler and a ribbon mixer, and a melting method such as an open roll, an extrusion mixer, a kneader and a Banbury mixer. There is a method of mixing. Among these methods, in order to obtain a more uniform resin composition, these mixing methods may be used in combination of two or more kinds (for example,
After pre-dry blending, the mixture is melt mixed). Even when using dry blending together, even when using one or two or more methods of melt-mixing, in producing a molded article by the molding method described below, it is particularly preferable to use pelletizing by manufacturing pellets. .

Among the above mixing methods, it is necessary to carry out at a temperature at which the resin used is melted, regardless of whether they are melt mixed or molded by the molding method described later. However, when it is carried out at a high temperature, the resin is thermally decomposed or deteriorated, so that it is generally carried out at 150 to 350 ° C, preferably 170 to 250 ° C.

The polypropylene resin composition of the present invention is molded into a desired shape by applying a molding method such as an injection molding method, an extrusion molding method, a compression molding method and a hollow molding method which are generally practiced in the field of synthetic resins. You may let me. Alternatively, after being formed into a sheet using an extrusion molding machine, this sheet may be formed into a desired shape by a secondary processing method such as a vacuum forming method or a pressure forming method.

[0021]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. In the following examples and comparative examples, each physical property was measured by the following methods. Izod impact strength (kgf · cm / cm) was measured with a notch at a temperature of −30 ° C. according to ASTM D265. Flexural modulus (kgf / cm ² ) is 23 according to ASTM D790.
It was measured at a temperature of ° C. The L value shown in Table 1 is 110 Hz in the dynamic viscoelasticity measurement method, and the heating rate is 2 ° C. /
A temperature sweep measurement was performed at min, and the tan δ value was temperature integrated within a range of −150 to −30 ° C.

The types and physical properties of (A) and (B) used in Examples and Comparative Examples are as follows.

(A) Polypropylene As polypropylene, MFR 30g / 1 shown in Table 1 is used.
Homotype polypropylene (PP-1) for 0 minutes and block type polypropylene (PP-2) with MFR of 40 g / 10 minutes and rubber content of 22% by weight were used.

(B) Ethylene / α-olefin structural elastomer The following elastomers shown in Table 1 were used. In both cases, the structure of the ethylene / α-olefin block is a random structure. Ethylene / propylene copolymer (EPR-1 to EPR-
4) Styrene-ethylene / propylene-styrene triblock copolymer (SEPS-1, SEPS-2), styrene-ethylene / propylene diblock copolymer (SE
P) Ethylene-ethylene / propylene-ethylene triblock copolymer (CEPC) Ethylene / butene copolymer (EBR-1, EBR-2) Styrene-ethylene / butene-styrene triblock copolymer (SEBS) Ethylene / hexene Copolymer (EHR) Ethylene / Octene Copolymer (EOR)

[0025]

[Table 1]

(Preparation of Test Piece) These components were blended in the proportions shown in Table 2 and dry blended for 5 minutes with a Henschel mixer. The obtained mixture was kneaded using a co-direction twin-screw extruder (diameter 30 mm) set at 210 ° C. to produce pellets. The pellets were injection-molded using an injection molding machine set at 230 ° C. to prepare test pieces for measurement. Table 2 shows the measurement results of Izod impact strength and flexural modulus of each test piece.

(Example 1) (A) PP-1, (B) B-
As shown in Table 2, the low temperature impact resistance and the rigidity of the resin composition obtained by blending 1 with 76% by weight and 24% by weight, respectively, were high.

(Comparative Examples 1 and 2) Comparative Examples 1 and 2
Is a combination of polypropylene and ethylene / propylene copolymer known in the prior art, and polypropylene, ethylene / propylene copolymer and ethylene, which are different from Example 1 only in the type of (B). And / or a butene copolymer. In both Comparative Example 1 and Comparative Example 2, the rigidity was about the same as that of Example 1, but the low temperature impact resistance was low.

(Examples 2 to 13) The resin compositions in which the types and composition ratios of (A) and (B) were changed as shown in Table 2 were excellent in low temperature impact resistance and rigidity.

(Comparative Examples 3 to 7) (B) with respect to Example 1
However, the resin compositions obtained in both cases had a poor balance between low temperature impact resistance and rigidity.

[0031]

[Table 2]

[0032]

The polypropylene resin composition of the present invention exhibits the following effects. (1) High rigidity. (2) Excellent low temperature impact resistance. The polypropylene resin composition of the present invention exerts the effects as described above, and thus is suitable as a material for industrial members.

Front page continued (72) Inventor Yoshihiro Mogi 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Akira Kawasaki Plastic Research Laboratory

Claims (1)

[Claims] 1. (A): 50 to 95% by weight of polypropylene, (B): when measured by temperature sweep in dynamic viscoelasticity measurement, It is composed of 5 to 50% by weight of an ethylene / α-olefin structure elastomer having an L value represented by the formula (1) of 15 to 100, and the total of the rubber component and (B) contained in (A) is 5.
A polypropylene-based resin composition, characterized in that the content is ˜50% by weight.