JPH08269262A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE: To obtain a polypropylene resin compsn. excellent in mechanical strengths (e.g. stiffness and impact strength), heat resistance, and surface hardness. CONSTITUTION: This compsn. comprises 70-99.5wt.% polypropylene resin having a xylene insol. content at 25 deg.C of 97.5wt.% or higher and an isotactic pentad fraction of 96.3% or higher and 30-0.5wt.% resin component obtd. by exposing a high-density polyethylene to an ionizing radiation.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene-based material which is excellent in mechanical strength such as rigidity and impact resistance, heat resistance and surface hardness, which is preferably used in the fields of automobile parts, electric / electronic parts and packaging materials. It relates to a resin composition.

[0002]

Polypropylene is generally inexpensive and
It is widely used as an industrial material for automobile parts, electric / electronic parts, and various packaging materials by taking advantage of its properties such as light weight, chemical resistance, acid resistance, and heat resistance. 2. Description of the Related Art In recent years, there has been a strong demand for improving the properties of polypropylene-based materials as products have higher functionality or cost competition. Among the above characteristics, a method of adding a nucleating agent as a method for improving rigidity, impact resistance and transparency (Japanese Patent Publication No. 39-1809, Japanese Patent Publication No. 60-139371, etc.) or a wide molecular weight distribution Polypropylene (JP-A-56-230
No. 7, Japanese Patent Laid-Open No. 62-195009) and the like have been proposed.

[0003]

However, although the above method improves the characteristics to some extent, the rigidity, heat resistance and impact resistance are still insufficient.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a polypropylene resin composition having physical properties that are less dependent on rigidity, heat resistance, and MFR.

[0004]

As a result of intensive studies, the present inventors have found that the above object can be achieved by a combination of a specific polypropylene resin and a high-density polyethylene treated with ionizing radiation. The present invention has been completed based on this finding.

That is, the present invention is a polypropylene comprising (A) 70 to 99.5% by weight of a polypropylene resin having the following physical properties and (B) 30 to 0.5% by weight of a resin-treated product obtained by subjecting high-density polyethylene to ionizing radiation treatment. A resin composition is provided. (A) Xylene extraction insoluble matter at 25 ° C. 97.5% by weight or more (b) Isotactic pentad fraction 96.3%
Hereinafter, the present invention will be specifically described.

The polypropylene resin (A) (hereinafter referred to as "PP") in the present invention is a homopolymer of propylene or propylene and 20% by weight or less of other α-olefins such as ethylene, butene-1,4-methyl. A block or random copolymer with pentene-1, octene-1, etc. is mentioned. These resins may be used alone or in combination of two or more, but it is necessary that they have the following physical properties. That is, the PP of the present invention is (a)
The xylene-extractable insoluble matter (hereinafter referred to as “XI”) at 25 ° C. is 97.5% by weight or more, preferably 98.0.
It is at least wt%, more preferably at least 98.5 wt%. When XI is less than 97.5% by weight, rigidity and heat resistance are poor. In addition, XI represents the ratio of the polymer precipitated by dissolving PP in ortho-xylene at 135 ° C. once and then cooling to 25 ° C. in% by weight.

The PP of the present invention has a (b) isotactic pentad fraction (hereinafter referred to as "IP") of 96.
It is 3% or more, preferably 97.0% or more, and particularly preferably 97.5% or more. If the IP is less than 96.3%, the rigidity and heat resistance are poor, which is not preferable. Note that I
P refers to the isotactic fraction in pentad units in the PP molecular chain. The measurement of IP uses a nuclear magnetic resonance apparatus ( ¹³ C-NMR) using isotopic carbon, and the method is, for example, A. Zambelli; Macromolecules, 6 , 925 (197).
3), the, 8, 587 (1975), the, 13, 267 (1980) there is a detailed description. As the PP satisfying the above, for example, a solid catalyst containing a magnesium compound, a titanium compound, a halogen-containing compound and an electron-donating compound as essential components is further represented by the general formula: TiXa.Yb (where X is Cl, Br, The highly stereoregular polypropylene obtained by polymerizing the halogen atom of I using a modified catalyst represented by a is 3 or 4 and b is an integer of 3 or less. Melt flow rate of PP (measured according to JIS K7210 at 230 ° C., load 2.16 kg, hereinafter “MF
"R") is usually 0.05 to 1000 g / 10 minutes, preferably 0.1 to 700 g / 10 minutes, and particularly preferably 0.5 to 500 g / 10 minutes.

The resin-treated product (B) in the present invention is high-density polyethylene (hereinafter referred to as "HDPE") treated by ionizing radiation. The HDPE is an ethylene homopolymer or ethylene and α having 3 to 12 carbon atoms.
-Copolymer with olefin and density 0.94 g /
cm ³ or more is preferable, and especially 0.95 g / c
It is preferably m ³ or more. The melt flow rate of HDPE (measured according to JIS K7210 at 190 ° C. and a load of 2.16 kg) is usually 1 to 1000 g / 10 minutes, preferably 2 to 700 g / 10 minutes, and particularly 3
~ 500 g / 10 min is preferred.

The ionizing radiation irradiation treatment can be performed on the HDPE powder or pellets under any conditions of high vacuum, inert gas or air. Examples of the ionizing radiation include X-rays, α-rays, γ-rays and electron rays, but γ-rays and electron rays are particularly preferable. The irradiation dose is generally 0.5 to 200 kGy, preferably 1 to 150 kGy, and particularly preferably 2 to 100 kGy. When the irradiation dose exceeds 200 kGy, the gel content tends to increase, and there is a possibility that problems may occur in terms of compatibility.

The composition ratio of the component (B) in the resin composition comprising the component (A) and the component (B) of the present invention is 0.5 to.
It is 30% by weight, preferably 0.7 to 25% by weight, and particularly preferably 1.0 to 20% by weight. If the composition ratio of the component (B) is less than 0.5% by weight, the improving effect is insufficient. On the other hand, if it exceeds 30% by weight, rigidity and heat resistance are deteriorated, which is not preferable.

The type of the rubber-like polymer (C) in the present invention is not particularly limited, and examples thereof include natural rubber or butadiene rubber, styrene-butadiene rubber, chloroprene rubber, styrene-isoprene rubber, acrylic rubber, butyl rubber, ethylene. -Synthetic rubber such as propylene rubber, styrene-ethylene / isoprene-styrene block copolymer (SEPS), styrene-ethylene / butylene-styrene block copolymer (SEBS)
And the like, such as a thermoplastic elastomer. The composition ratio of the component (C) in the resin composition of the present invention is 5 to
50% by weight is preferable, and 10 to 40% by weight is particularly preferable.

Further, the (D) nucleating agent in the present invention is
In the field of synthetic resins, it refers to a substance that is added to a crystalline resin such as polypropylene and has the effect of becoming a nucleus of crystals to grow crystals, and various substances are known. Examples include metal salts of carboxylic acids, dibenzylidene sorbitol derivatives, phosphate alkali metal salts, and inorganic compounds such as talc. Specific examples include sodium benzoate, aluminum adipate, aluminum-pt-
Butyl benzoate, 1,3,2,4-dibenzylidene sorbitol, 1,3,2,4-bis (p-methylbenzylidene) sorbitol, 1,3,2,4-bis (p-
Ethylbenzylidene) sorbitol, 1,3-p-chlorobenzylidene-2,4-p-methylbenzylidenesorbitol, sodium-bis (4-t-butylphenyl)
Phosphate, sodium-bis (4-t-methylphenyl) phosphate, potassium-bis (4,6-di-phosphate
t-Butylphenyl) phosphate, sodium-2-
2'-methylene-bis (4,6-di-t-butylphenyl) phosphate, sodium-2-2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate and talc, calcium carbonate And so on. These nucleating agents may be used alone or in combination of two or more.

The blending ratio of the nucleating agent is generally 0.05 to 20 parts by weight with respect to 100 parts by weight of the resin content, and there is a preferable ratio depending on the kind. In the case of an organic system excluding inorganic compounds, it is usually 0.05 to 1.0 part by weight, and 0.08 to
0.8 parts by weight is preferable, and 0.1 to 0.5 parts by weight is particularly preferable. On the other hand, in the case of an inorganic compound such as talc and high-density polyethylene, it is usually 1 to 20 parts by weight, preferably 2 to 18 parts by weight, particularly 5 to 15 parts by weight. When an inorganic compound is used, it may be treated with a titanate-based, silane-based, aluminum-based coupling agent, a surface treatment agent such as a fatty acid, a fatty acid metal salt, or a fatty acid ester.

The resin composition of the present invention can be obtained by a conventionally known mixing method of the above components. For example, there is a method in which a Henschel mixer, a ribbon mixer or the like is used for mixing, and then a mixing roll, a Banbury mixer, a kneader, an extruder or the like is used for melt mixing. The temperature for melt mixing is generally 170 to 3
The temperature is 00 ° C., and it is preferably performed in the range of 180 to 270 ° C. Further, the resin composition of the present invention, if desired, various conventional additives such as antioxidants, weather resistance stabilizers, antistatic agents, lubricants, antifogging agents, electrical property improvers, processability improvers, pigments, A softening agent or the like may be added within a range that does not impair the object of the present invention.

[0015]

The present invention will be described in more detail with reference to the following examples. In addition, MFR of polypropylene is JIS K7
According to No. 210, the measurement was performed under the condition 14 in Table 1. The MFR of high-density polyethylene is based on JIS K7210, Table 1,
It was measured under the condition 4. The flexural modulus was based on JIS K7203. The Izod impact strength was measured with a notch according to JIS K7110. Deflection temperature under load is JIS
It was based on the K7207B method. Rockwell hardness is JI
It was measured with a scale R according to SK7202. Also,
The IP measurement conditions are as follows. Measuring instrument: JNM-GSX400 manufactured by JEOL Ltd. Measuring mode: Proton decoupling method Pulse width: 8.0 μs Pulse repetition time: 5.0 s Accumulation frequency: 20000 times Solvent: 1,2,4-trichlorobenzene / heavy benzene Mixed solvent (75/25% by volume) Internal circulation: Hexamethyldisiloxane Sample concentration: 300 mg / 3.0 ml Solvent measurement temperature: 120 ° C

Further, as polypropylene of the component (A), homopolypropylene having MFR of 0.6 g / 10 minutes, XI of 98.8% by weight and IP of 98.2% (hereinafter referred to as "PP-
1 "), MFR 10.5g / 10 minutes, XI 9
Homopolypropylene (hereinafter referred to as "PP-2") having 9.3 wt% and IP of 98.8% and MFR of 3
Homopolypropylene having 4.8 g / 10 minutes, XI of 99.2% by weight, and IP of 98.7% (hereinafter referred to as "PP-
3 ”) was used. For comparison, a homopolypropylene having a MFR of 4.2 g / 10 minutes, an XI of 97.0% by weight, and an IP of 95.6% (hereinafter referred to as "PP-
A ”) was used.

As the component (B) HDPE, the MFR is 2
2 g / 10 minutes with a density of 0.956 g / cm ³ (hereinafter referred to as “PE-1”) and MFR of 5.2 g
/ 10 minutes and the density was 0.956 g / cm ³ (hereinafter referred to as “PE-2”). As the rubber-like polymer of the component (C), (Mitsui Petrochemical Co., Ltd., Tuffmer P-0480) (hereinafter referred to as “RB-1”) and (Asahi Kasei Co., Ltd., Tuftec H1052) (hereinafter referred to as “RB-2”) are used. Using. Furthermore, as the component (D), 2,2-methylene-bis (4,6-di-t-phosphate) is used.
-Butylphenyl) sodium was used.

Production Example of Component (B) (XPE-1 to 4) HDPE shown in the following Table 1 as the component (B) is a γ-ray irradiation device (manufactured by Koga Isotope Co.) or an electron beam irradiation device (Nisshin). Irradiation doses shown in Table 1 were applied under a nitrogen atmosphere by using High Voltage. Then, heat treatment was performed at 130 ° C. for 30 minutes in a nitrogen atmosphere. Then, MFR was measured and the results are shown in Table 1.

[0019]

[Table 1]

Examples 1 to 10 and Comparative Examples 1 to 3 (A) component whose type and blending amount are shown in Table 2,
As the component (B) and the component (C) and the stabilizer, di-
0.05 parts by weight of t-butyl-p-cresol, pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-butylhydroxyphenyl) propionate]
0.1 parts by weight and 0.1 parts by weight of calcium stearate are used as a super mixer (Kawata Seisakusho, SMV20 type).
After mixing using a twin-screw extruder (Nakaya Seisakusho, AS
30 type) was kneaded at a temperature of 230 ° C. to form pellets. When the component (D) was added, it was blended during the above kneading. Using an injection molding machine (manufactured by Toshiba Machine Co., IS-170F11), the obtained pellets were used to prepare test pieces at a temperature of 230C. The test piece thus obtained was allowed to stand in a thermostatic chamber at a relative humidity of 50% and a temperature of 23 ° C. for 2 days, and then the flexural modulus, Izod impact strength (with notch), deflection temperature under load and Rockwell hardness were measured. Table 2 shows the above results.

[0021]

[Table 2]

[0022]

The resin composition of the present invention is excellent in mechanical strength such as rigidity and impact resistance, heat resistance, and surface hardness, and is therefore useful in various fields such as automobile parts, electric / electronic parts and packaging materials. Is.

Claims (4)

[Claims] 1. A polypropylene resin having the following physical properties (A) 70 to 99.5% by weight, and (B) a high-density polyethylene treated with ionizing radiation, a resin-treated product 30 to 0.5.
A polypropylene-based resin composition comprising 10% by weight. (A) Xylene extraction insoluble matter at 25 ° C. 97.5% by weight or more (b) Isotactic pentad fraction 96.3%
that's all 2. The polypropylene resin composition according to claim 1, which is 50 to 95% by weight, and (C) a rubber-like polymer.
A polypropylene resin composition comprising 0 to 5% by weight. 3. The (D) nucleating agent 0.05-2 with respect to 100 parts by weight of the resin composition according to claim 1 or 2.
A polypropylene resin composition containing 0 parts by weight. 4. The polypropylene-based fat composition according to claim 1, wherein the ionizing radiation is γ ray or electron beam.