JPH08302097A - Polypropylene resin composition and injection molded product - Google Patents

Abstract

PURPOSE: To obtain a polypropylene resin composition exhibiting a high impact- resistant strength and simultaneously excellent in whitening resistance, and to obtain its injection molded product. CONSTITUTION: A polypropylene resin composition comprises (A) 100 pts.wt. of a polypropylene resin, (B) 3-300 pts.wt. of an ethylene/propylene copolymer elastomer, and (C) 1-300 pts.wt. of an ethylene/α-olefin copolymer elastomer satisfying the below-described requirements (a)-(d). (a) The number of carbon atoms contained in the α-(4-2OC)olefin is 4-20. (b) The content of the α-olefin is 65-95 wt.%. (c) The density of the elastomer is <0.88g/cm<2> at 23 deg.C. (d) The melting peak of a crystal is not observed by the use of a differential scanning calorimeter.

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, and more particularly to a polypropylene resin composition having high impact resistance and excellent whitening resistance, and an injection molded product thereof. .

[0002]

2. Description of the Related Art A polypropylene resin (hereinafter referred to as PP) is often blended with an elastomer represented by an ethylene / propylene copolymer elastomer (hereinafter referred to as EPR) for the purpose of improving cold resistance and impact resistance. Are known. However, although the elastomer blend improves cold resistance and impact resistance, it causes serious whitening when impact is applied or when it is bent. Particularly for automobile products, a method of fitting and assembling parts is being adopted for the purpose of simplifying the work process, and there is a strong demand for a product that is not bleached due to an impact at the time of fitting. Also,
Improvements in home appliances, containers, daily necessities, etc. have been strongly desired because their commercial value is impaired when they are bleached.

Further, in the case of injection-molding PP modified by EPR, pursuit of shortening the molding cycle may cause whitening due to the protruding pin, which causes many problems such as restrictions on the product shape.

PP thus modified by EPR
However, the conventional composition cannot meet the needs of the market, which is a big problem.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is a polypropylene resin composition and an injection-molded article which show high impact resistance and excellent whitening resistance. Is provided.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, completed the present invention. That is, the present invention relates to 100 parts by weight of polypropylene resin (A), 3 to 300 parts by weight of ethylene / propylene copolymer elastomer (B), and an ethylene / α-olefin copolymer satisfying the requirements of (a) to (d). The present invention relates to a polypropylene resin composition comprising 1 to 300 parts by weight of an elastomer (C) and an injection molded product thereof.

(A) Carbon number of α-olefin is 4 or more 2
0 or less (b) The content of α-olefin is more than 65% by weight and 95
Weight% or less (c) Density at 23 ° C. is less than 0.88 g / cm ³ (d) No crystal melting peak is observed by a differential scanning calorimeter. The details will be described below.

As the polypropylene resin (A) used in the present invention, a generally used crystalline polypropylene resin can be used. For example, a polypropylene homopolymer, a propylene / ethylene random copolymer having an ethylene content of 0.5 to 12% by weight, an ethylene content of 0.5 to 12% by weight, and an α-olefin content such as butene-1 of 0. 5 to 20 wt% propylene / ethylene / α-olefin terpolymer, ethylene content 1 to 6
0% by weight of impact PP (sometimes referred to as block PP), a crystalline polypropylene-based resin having a syndiotactic structure, and the like are used, and one or more of these are used.

The melt flow rate of the polypropylene resin (A) is not particularly limited, but is 230 ° C., 2.16.
It is preferable to use one having a load of 0.01 to 100 g / 10 min under a load of kg.

The ethylene / propylene copolymer elastomer (B) used in the present invention preferably has a propylene content of 5% by weight or more and 85% by weight or less from the viewpoint of improving impact strength, and more preferably 10% by weight or more 75%. When the content is less than or equal to% by weight, cold resistance is improved, which is desirable.

The Mooney viscosity of the ethylene / propylene copolymer elastomer (B) used in the present invention is M.
It is desirable that L1 + 4 (100 ° C.) is not less than 5 and not more than 150 in order to exhibit excellent impact resistance and moldability.
It is more preferably 0 or more and 100 or less because the dispersibility in the polypropylene resin is improved.

The amount of ethylene / propylene copolymer elastomer (B) added is 100% polypropylene resin (A).
The amount is preferably 3 parts by weight or more and 300 parts by weight or less with respect to parts by weight, and if less than 3 parts by weight, impact strength may decrease. If it exceeds 300 parts by weight, the composition of the present invention may be molded. It may be difficult to maintain its shape. Further, when high rigidity is required for the composition of the present invention, it is desirable that the addition amount of the ethylene / propylene copolymer elastomer (B) be 45 parts by weight or less.

Ethylene / α-used in the present invention
The α-olefin of the olefin copolymer elastomer (C) has 4 to 20 carbon atoms, and includes, for example, butene-1, pentene-1, hexene-1, 4-methyl-pentene-1, heptene-1, Octene-1, Nonene-
1, decene-1, undecene-1, dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-
1, nonadecene-1, eicosene-1, and the like, and one or more of these are used. Among them, butene-1, heptene-1, and hexene- are easily available.
1, octene-1 and the like are preferable.

Ethylene / α-used in the present invention
The α-olefin content of the olefin copolymer elastomer (C) is more than 65% by weight and 95% by weight or less, preferably 70% by weight or more and 90% by weight or less. When the α-olefin content is 65% by weight or less, the whitening property of the obtained resin composition is poor. Also, the α-olefin content is 95% by weight.
If it is more, the glass transition temperature of the ethylene / α-olefin copolymer elastomer will increase and the cold resistance of the resulting resin composition will decrease.

Ethylene / α-used in the present invention
The density of the olefin copolymer elastomer (C) at 23 ° C. is less than 0.88 g / cm ³ . Density 0.8
With an ethylene / α-olefin copolymer of 8 g / cm ³ or more, the resulting resin composition may be inferior in whitening resistance.

Ethylene / α-used in the present invention
The olefin copolymer elastomer (C) is characterized in that no crystal melting peak is observed by a differential scanning calorimeter (abbreviated as DSC). When an ethylene / α-olefin copolymer showing a crystal melting peak is used, the whitening property of the obtained resin composition is lowered.

Ethylene / α-used in the present invention
The molecular weight of the olefin copolymer elastomer (C) is not particularly limited, but the number average molecular weight measured by gel permeation chromatography (GPC) is preferably 5,000 to 1,000,000 in terms of polyethylene, and more preferably 10,000-60
It is 0000. If the number average molecular weight is less than 5,000, the surface of the obtained resin composition may become sticky, while if the number average molecular weight exceeds 1,000,000, the fluidity of the obtained resin composition is lowered and molding process becomes difficult. There is a risk.

Ethylene / α-used in the present invention
The molecular weight distribution (Mw / Mn) of the olefin copolymer elastomer (C) is not particularly limited, but is preferably 3 or less. It is generally known that the larger the molecular weight distribution, the larger the composition distribution. When the composition distribution is wide, ethylene /
The compatibility between the α-olefin copolymer elastomer (C) and the polypropylene resin (A) becomes poor, and it becomes difficult to obtain a resin composition having excellent whitening performance. 10% of high molecular weight fraction fractionated by GPC as an index of composition distribution
The ratio of the average α-olefin content (mol%) in the 10% low molecular weight cut to the average α-olefin content (mol%) in is used. The ratio of both is preferably 1.2 or less, more preferably 1.15 or less.

The ethylene / α-olefin copolymer elastomer (C) is added in the amount of polypropylene resin (A).
The amount is preferably 1 part by weight or more and 300 parts by weight or less with respect to 100 parts by weight, and can be arbitrarily changed according to the intended use and required physical properties. However, if it is less than 1 part by weight, the whitening property of the obtained resin composition may be poor, and if it exceeds 300 parts by weight, the heat resistance of the obtained resin composition may be impaired. Further, when high rigidity is required for the resin composition of the present invention, it is desirable that the addition amount of the ethylene / α-olefin copolymer elastomer (C) be 45 parts by weight or less.

The method for producing the ethylene / α-olefin copolymer elastomer (C) described above is not particularly limited,
It can be produced using various catalysts such as a titanium-based catalyst, a vanadium-based catalyst, or a metallocene-based catalyst. Above all, it is preferable to use a metallocene-based catalyst that is easy to obtain an ethylene / α-olefin copolymer elastomer satisfying the above-mentioned molecular weight, molecular weight distribution and composition distribution.

That is, (a) a transition metal compound containing a transition metal of Group 4 of the periodic table, (b) a compound which reacts with this to form an ionic complex, and (c) an organometallic compound, if necessary. An ethylene / α-olefin copolymer elastomer can be produced by copolymerizing ethylene and an α-olefin in the presence of a catalyst consisting of

Polymerization can be carried out by any of batch method, semi-continuous method and continuous method, and it can also be carried out in two or more stages by changing the polymerization conditions. Further, the copolymer obtained after the completion of the polymerization is separated and recovered from the polymerization solution by a conventionally known method and dried to obtain a solid copolymer.

In the resin composition of the present invention, it is desirable that the long period, which is the average distance of the centers of gravity of the crystals, be larger than that obtained by molding the polypropylene resin (A) alone. Due to this property, the resin composition of the present invention is obtained. The whitening property of is even more excellent.

The resin composition of the present invention preferably has a glass transition temperature of the PP phase, which is evaluated by the temperature dependence of dynamic viscoelasticity, lower than that of the polypropylene resin (A) by 1 ° C. or more. The whitening property is further improved by this property. In dynamic viscoelasticity, the glass transition temperature can be evaluated as the maximum temperature of the loss tangent (tan δ).

The composition of the present invention contains calcium carbonate, mica, talc, silica, barium sulfate, calcium sulfate, kaolin, clay, pyroferrite, if necessary.
Bentonite, serisanite, zeolite, nepheline sinite, attapulgite, wollastonite, ferrite, calcium silicate, magnesium carbonate, dolomite, antimony trioxide, zinc oxide, titanium oxide, magnesium oxide, iron oxide, molybdenum disulfide, graphite, gypsum , Glass beads, glass powder, glass balloons,
Inorganic fillers such as glass fiber, quartz, and quartz glass can be added, and they are preferably used when the rigidity of the composition is important. In this case, it is preferable to use an inorganic filler whose surface is modified with a polar group because it has excellent dispersibility. In addition, the composition of the present invention includes organic and inorganic pigments, as well as crystal nucleating agents, clarifying agents, antiblocking agents, release agents, antistatic agents, slip agents, antifog agents, lubricants,
A heat resistance stabilizer, an ultraviolet light stabilizer, a weather resistance stabilizer, a foaming agent, a mildewproofing agent, a rust preventive agent, an ion trap agent, a flame retardant, a flame retardant auxiliary agent, and the like may be added as necessary. Furthermore, high density polyethylene, linear low density polyethylene, branched low density polyethylene, to the extent that the performance of the composition of the present invention is not impaired,
Ethylene / vinyl acetate copolymer, polybutene-1, poly-4-
It is also possible to add methyl-pentene-1 and the like.

The resin composition of the present invention is prepared by a method which is usually used, such as polypropylene resin (A), ethylene / propylene copolymer elastomer (B) and ethylene / α.
-Although it can be obtained by blending the olefin copolymer elastomer (C), it is preferably produced by melt blending using a kneader, roll, Banbury mixer, extruder or the like. The order of blending is not limited, and all the components may be blended at the same time, or any two components may be blended in advance.

The polypropylene-based resin composition of the present invention is molded by injection, compression, film, profile extrusion, vacuum, compressed air, transfer and blow molding, and the resulting molded article exhibits high impact strength and has a whitening property. It is an excellent molded product suitable for automobile interior materials, home appliances, daily necessities, containers, etc. Particularly in injection molding, the probability of whitening of the molded product due to the ejecting pin is greatly reduced in the ejecting step after the cooling step, and the yield is improved.

[0028]

The present invention will be described below with reference to examples, but these are illustrative and not limiting. Various measurements in Examples and the synthesis of ethylene / α-olefin copolymer elastomers were carried out by the following methods.

(Α of ethylene / α-olefin copolymer
—Measurement of Olefin Content) It was calculated by measuring ¹³ C-NMR spectrum (JNM GX400 manufactured by JEOL Ltd.) in o-dichlorobenzene as a solvent at 100 MHz.

(Measurement of molecular weight and molecular weight distribution)
Gel permeation chromatography (manufactured by Millipore Corporation) at 140 ° C. using dichlorobenzene.
It was calculated in terms of polyethylene by using 150C type GPC).

Reference Example 1 Synthesis of ethylene / butene-1 copolymer elastomer 1000 ml of toluene and 500 ml of butene-1 were added to a 5 l autoclave and the temperature was raised to 40 ° C. Furthermore, ethylene was introduced so that the total pressure would be 8 kg / cm ² . Then, in another reaction container, 10 ml of toluene, 5 mmol of methylaluminoxane, (dimethyl (t-butylamide) (tetramethyl-η5-cyclopentadienyl))
After adding 5 μmol of titanium (silane) dichloride and stirring the mixed solution for 20 minutes, the mixture was introduced into an autoclave to start polymerization. This polymerization has a total pressure of 8 kg / cm ^2.
Ethylene was continuously introduced to keep
Minutes.

After the completion of the polymerization, the polymer was washed with a large amount of ethanol and dried under reduced pressure at 60 ° C. for 12 hours. As a result, 44 g of an ethylene / butene-1 copolymer elastomer having a butene-1 content of 72% by weight was obtained. Number average molecular weight 108,000, Mw / Mn = 2.2, density 0.86
It was 4 g / cm ³ .

Example 1 Polypropylene homopolymer (Tosoh Polypro J5100
A, MFR: 11 g / 10 min) 126 g, ethylene / propylene copolymer elastomer (JSREP11, ML
_{1 + 4} (100 ° C) = 42, manufactured by Japan Synthetic Rubber Co., Ltd. 36 g,
18 g of the ethylene / butene-1 copolymer elastomer obtained in Reference Example 1, 1 g of carbon black, and a hindered phenolic stabilizer (Irganox 1) as a heat stabilizer.
010 (manufactured by Ciba Geigy)) and 2 phosphorus stabilizers (Irgafos 168 (manufactured by Ciba Geigy))
000ppm, calcium stearate as a lubricant: 5
000ppm for Labo Plastomill (internal volume 200cc)
Was melt-blended at 60 rpm for 5 minutes at 200 ° C. Then, the obtained composition was finely broken and molded into a flat plate having a thickness of 2 mm and an Izod test piece having a thickness of 3.2 mm by an injection molding machine (Minimat, manufactured by Sumitomo Heavy Industries, Ltd.).

Reference Example 2 Synthesis of ethylene / butene-1 copolymer elastomer 400 ml of toluene and 1100 ml of butene-1 were added to a 5 l autoclave and the temperature was raised to 40 ° C. Furthermore, ethylene was introduced so that the total pressure would be 8 kg / cm ² . Next, 10 ml of toluene, 3 mmol of methylaluminoxane, and 3 μmol of diphenylmethane (cyclopentadienyl-1-fluorenyl) zirconium dichloride were added to another reaction vessel, and the mixed solution was stirred for 20 minutes and then introduced into an autoclave to start polymerization. did.
This polymerization was carried out at 40 ° C. for 60 minutes by continuously introducing ethylene so that the total pressure was kept at 8 kg / cm ² .

After completion of the polymerization, the polymer was washed with a large amount of ethanol and dried under reduced pressure at 60 ° C. for 12 hours. As a result, 102 g of an ethylene / butene-1 copolymer elastomer having a butene-1 content of 77% by weight was obtained. Number average molecular weight 45,000, Mw / Mn = 2.6, density 0.86
It was ³ g / cm ³ .

Various ethylene / butene-1 copolymer elastomers were obtained by performing the same operation as above while changing the amount of butene-1. Also, butene-1 was changed to hexene-1 and propylene to obtain various ethylene / α-olefin copolymer elastomers. The copolymers used are summarized in Table 1.

Example 2 Instead of the ethylene / butene-1 copolymer elastomer used in Example 1, ethylene / butane-1 obtained in Reference Example 2 was used.
Using butene-1 copolymer elastomer, a test piece was obtained in the same manner as in Example 1.

Example 3 Instead of the ethylene / butene-1 copolymer elastomer used in Example 1, the hexene-1 content was 77% by weight.
Using the ethylene / hexene-1 copolymer elastomer of, a test piece was obtained in the same manner as in Example 1.

Example 4 Impact PP (Tosoh Polypro J7090B ethylene content: 7.0%, MF, instead of propylene homopolymer)
R: 9.0 g / 10 min) was used to obtain a test piece in the same manner as in Example 1.

Example 5 A test piece was obtained in the same manner as in Example 4 except that 5 g of talc (manufactured by Fuji Talc, LSM # 300) was added.

Comparative Example 1 A test piece was obtained in the same manner as in Example 1 except that the ethylene / butene-1 copolymer elastomer was not added.

Comparative Example 2 A test piece was obtained in the same manner as in Example 1 except that the ethylene / propylene copolymer elastomer was not added.

Comparative Example 3 The same as Example 1 except that the ethylene / butene-1 copolymer elastomer used in Example 1 was replaced by an ethylene / butene-1 copolymer elastomer having a butene-1 content of 53% by weight. A test piece was obtained by the method.

COMPARATIVE EXAMPLE 4 An ethylene / propylene copolymer elastomer having a propylene content of 75% by weight was used in place of the ethylene / butene-1 copolymer elastomer used in Example 1 and tested in the same manner as in Example 1. Got a piece.

Reference Example 3 Synthesis of ethylene / butene-1 copolymer elastomer 500 ml of toluene and 1000 ml of butene-1 were added to a 5 l autoclave and the temperature was raised to 40 ° C. Further, ethylene was introduced so that the total pressure would be 4 kg / cm ² . Next, 10 ml of toluene, 3 mmol of methylaluminoxane, and dimethylsilylbis (2-
Methylindenyl) zirconium dichloride 3μmo
1 was added, the mixed solution was stirred for 20 minutes, and then introduced into an autoclave to initiate polymerization. This polymerization was carried out at 40 ° C. for 30 minutes by continuously introducing ethylene so as to keep the total pressure at 4 kg / cm ² .

After completion of the polymerization, the polymer was washed with a large amount of ethanol and dried under reduced pressure at 60 ° C. for 12 hours. As a result, 54 g of an ethylene / butene-1 copolymer elastomer having a butene-1 content of 96% by weight was obtained. The number average molecular weight is 76000, Mw / Mn = 2.4, and the density at 23 ° C. is 0.882 g / cm ^3, which is measured by DSC.
The crystal melting point measured as the main peak was 45 ° C.

Comparative Example 5 The ethylene / butene-1 copolymer elastomer obtained in Synthesis Example 3 was used in place of the ethylene / hexene-1 copolymer elastomer used in Example 1, and the same method as in Example 1 was used. A test piece was obtained.

Comparative Example 6 A test piece was obtained in the same manner as in Example 5 except that the ethylene / butene-1 copolymer elastomer was not added.

Comparative Example 7 A test piece was obtained in the same manner as in Example 5 except that the ethylene / propylene copolymer elastomer was not added.

The test pieces obtained above were evaluated by the following methods. The results are shown in Table 1.

[0051]

[Table 1]

(Izod Impact Test) An Izod impact test was conducted in accordance with JIS K7110. Maximum capacity is 1.96
J and impact speed were 3.35 m / sec. The test temperature was changed depending on the type of polypropylene resin used, and it was -20 ° C. when using impact PP and 0 ° C. when using PP homopolymer.

(Impact whitening test) Height 80 ° C. at 23 ° C.
From the cm, the impacted body having a load of 1000 g and an impact weight diameter of 0.5π was dropped on a flat plate, and the test piece after 1 hour was visually observed to evaluate the whitened area. A flat plate having a pedestal inner diameter of 43 mm and a diameter of 2 mm was cut into 50 mm × 50 mm and used.

[0054]

As described above, the resin composition of the present invention is a polypropylene-based resin composition exhibiting high impact resistance and excellent whitening resistance, and is less likely to be whitened by the ejection pin during injection molding. It can be seen that an excellent injection-molded body can be provided.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // B29K 23:00

Claims (2)

[Claims] 1. A polypropylene resin (A) (100 parts by weight) and an ethylene / propylene copolymer elastomer (B).
3 to 300 parts by weight, ethylene / α-olefin copolymer elastomer (C) 1 to satisfy the requirements of (a) to (d)
A polypropylene resin composition comprising 300 parts by weight. (A) Carbon number of α-olefin is 4 or more and 20 or less (b) Content of α-olefin is more than 65% by weight 95
Weight% or less (c) Density at 23 ° C. is less than 0.88 g / cm ³ (d) No crystal melting peak is observed by differential scanning calorimeter 2. A molded article produced by injection-molding the composite material according to claim 1.