JPH08302088A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE: To obtain a thermoplastic resin composition comprising a specific polypropylene and a specified ethylene-α-olefinic copolymer rubber, and improved in low temperature impact resistance and heat-resistant rigidity. CONSTITUTION: The polypropylene resin composition comprises (1) 20-95wt.% of (A) polypropylene comprising the below-described polymers (i) and (ii) [(i): propylene homopolymer having a fine crystal size of 280Å or larger, wherein the fine crystal size is calculated from the half-value width of a diffraction peak exhibiting a (040) surface obtained by the measurement of the wide angle X-ray diffraction, and (ii): a propylene block copolymer wherein the propylene homopolymer portion of the first segment has a fine crystal size of >=280Å], (2) 5-40wt.% of (B) the below-described ethylene-α-olefinic copolymer rubber and/or its rubber composition [an ethylene-α-olefinic copolymer rubber and its rubber composition wherein, when kneaded with the polypropylene (A), the fine crystal size of the kneaded product is not lowered in a magnitude of >=5% in comparison with the fine crystal size of the polypropylene (A)], and (3) 0-40wt.% of (C) an inorganic filler.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene resin composition. Specifically, a polypropylene-based resin composition comprising polypropylene having a defined microcrystal size and a rubber composition that does not reduce the crystallite size, and polypropylene having a crystallite size and a rubber composition that does not reduce the crystallite size and an inorganic filler The present invention relates to a polypropylene resin composition containing an agent. Such a composition is excellent in mechanical properties, particularly rigidity, heat resistance and impact resistance, and provides a polypropylene resin composition suitable for use in, for example, automobile parts.

[0002]

2. Description of the Related Art In recent years, polypropylene, particularly ethylene-propylene block copolymer, has been widely used as a molding material for various parts. This ethylene-propylene block copolymer has an excellent balance of flexural modulus, heat distortion temperature, and impact strength, but has drawbacks such as low low-temperature impact strength for automobile bumpers. In order to improve low temperature impact resistance, it is preferred to blend an ethylene-propylene block copolymer with an ethylene-propylene copolymer rubber and the like, JP-A-53-22552 and JP-A-53-400.
No. 45, etc. However, since the ethylene-propylene copolymer rubber is compounded, the thermal properties such as flexural modulus and heat distortion temperature are inferior, and in order to solve this, calcium carbonate, barium sulfate, mica, crystalline calcium silicate and talc are further added. Incorporation of an inorganic filler such as that described in JP-A Nos. 51-136735 and 53-53
-64256, 53-64257, 57-55.
No. 952, No. 57-207630, No. 58-1713.
No. 9, No. 58-111846, No. 59-98157.
And Japanese Patent Publication No. 55-3374. Further, a resin composition having improved flexural modulus, surface hardness, etc. by increasing the isotactic pentad fraction of the propylene homopolymerized portion of polypropylene or ethylene-propylene block copolymer is disclosed in JP-A-5-5.
No. 9251 and No. 5-230321 are proposed. However, recently, there has been a demand for further improvement in heat resistance and rigidity by online coating of exterior parts such as automobile bumper materials. The low temperature impact resistance and the heat resistance are contradictory performances, and there is a limit in the conventional technique to improve the heat resistance without impairing the low temperature impact resistance.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, an object of the present invention is to use a specific polypropylene and a specific ethylene-α-olefin copolymer rubber,
It is intended to provide a polypropylene resin composition having improved heat resistance and impact resistance.

[0004]

The present invention provides (1) a polypropylene (A) comprising the following (i) and / or (ii): 20 to 95% by weight, and (i) a wide-angle X-ray diffraction measurement. The propylene homopolymer having a crystallite size of 280 A or more calculated from the half-width of the diffraction peak indicating the (040) plane is (ii) obtained by wide-angle X-ray diffraction measurement of the propylene homopolymer of the first segment ( 040) ethylene-propylene block copolymer having a crystallite size of 280 A or more calculated from the half width of the diffraction peak indicating the (0) plane (2) the following ethylene-α-olefin-based copolymer rubber and / or rubber composition (B): 5-40% by weight, when kneaded with polypropylene (A), half-width of diffraction peak showing (040) plane obtained by wide-angle X-ray diffraction measurement of the kneaded product Ri crystallite size calculated is, the polypropylene does not decrease more than 5% than the crystallite size indicated by (A) an ethylene -α- olefin copolymer rubber and /
Alternatively, the present invention relates to a polypropylene resin composition containing a rubber composition (3) an inorganic filler (C): 0 to 40% by weight.
Hereinafter, the present invention will be described in detail.

The polypropylene (A) used in the present invention means (i) a propylene homopolymer, that is, a homopolymer of crystalline propylene, or (ii) an ethylene-propylene block copolymer, that is, a crystalline polymer as the first segment. It has a propylene homopolymer part and an ethylene-propylene random copolymer part as the second segment. These may be used alone or in combination. The polypropylene (A) of the present invention is calculated from the full width at half maximum of the diffraction peak showing the (040) plane of the polypropylene crystal obtained by the wide-angle X-ray diffraction measurement of a propylene homopolymer or an ethylene-propylene block copolymer. The crystal size is 280 A or more. When the crystallite size is less than 280 A, it is difficult to obtain the effect of improving rigidity and heat resistance rigidity. When the ethylene-propylene block copolymer is used for the polypropylene (A) of the present invention, the ethylene content of the ethylene-propylene random copolymer portion as the second segment is 20 to 70% by weight, preferably 25 to 60%. % By weight. The ethylene-propylene random copolymer portion, which is the second segment in the ethylene-propylene block copolymer, is 5 to 40% by weight, preferably 10 to 3
0% by weight.

The term "fine crystallite size" as used herein means that the propylene homopolymer or the ethylene-propylene block copolymer was subjected to wide-angle X-ray diffraction measurement, and G. It is calculated from the full width at half maximum of the diffraction peak of the (040) plane of the polypropylene crystal defined by Natta et al. Specifically, regarding the diffraction pattern obtained by the wide-angle X-ray diffraction measurement, G. Natta
A.Weidinger and PHHermans Die Makromo
lekulare Chemie 98-115 , 50 (1961)) to create a baseline excluding the amorphous component of polypropylene,
G. The full width at half maximum is determined from the diffraction peak corresponding to the (040) plane of the α crystal of polypropylene defined by Natta et al. The half-width is substituted into the Scherrer's formula below to calculate the crystallite size. D = (Kλ) / {(B−b) cos θ} (Sche
rrr's formula) D: crystallite size (A) K: Scherrer constant = 0.9 λ: wavelength of Kα ray of Cu = 1.5405 (A) θ: diffraction peak angle (rad) B: half value width (rad) b: Half-width of the diffraction peak of an infinite crystal (rad) Here, an infinite crystal ideally has a half-width of 0, but a peak width is generated depending on the accuracy of the device.
b is used as a correction term for the device accuracy. As the infinite crystal, powdered silicon (# 200 mesh manufactured by Mitsuwa Chemical Co., Ltd.) is used.

In the ethylene-propylene block copolymer, the weight ratio X of the ethylene-propylene random copolymer portion to the whole block copolymer is
The heat of crystal fusion of each of the propylene homopolymerized portion and the whole block copolymer can be measured and calculated by the following equation. X = 1- (ΔHf) _T / (ΔHf) _P (ΔHf) _T : heat of fusion of the entire block copolymer (ca
1 / g) (ΔHf) _P : heat of fusion of homopolymerized portion of propylene (cal / g) The ethylene content is determined by the characteristic absorption of methyl group and methylene group appearing in the infrared absorption spectrum measured by making a press sheet. By the calibration curve method using the absorbance of. The ethylene content of the ethylene-propylene random copolymer portion can be calculated by measuring the ethylene content of the entire block copolymer and calculating from the following formula. (C ₂ ') _EP = (C ₂ ') _T / X (C ₂ ') _T : ethylene content (% by weight) of the entire block copolymer (C ₂ ') _EP : ethylene-propylene random copolymer part Ethylene content (wt%)

The ethylene-α-olefin copolymer rubber and / or rubber composition (B) used in the present invention is
The crystallite size calculated from the full width at half maximum of the diffraction peak showing the (040) plane obtained by wide-angle X-ray diffraction measurement of the mixture with the polypropylene (A) was 5% from the crystallite size shown in the polypropylene (A). It is a rubber and / or rubber composition (B) that does not decrease above. If it is decreased by 5% or more, mechanical properties such as rigidity and heat resistance are deteriorated, which is not preferable.

The ethylene-α-olefin copolymer rubber is a copolymer of ethylene and α-olefin or a terpolymer of ethylene, α-olefin and non-conjugated diene. Examples of the α-olefin include propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1 and the like, among which propylene and butene-1 are preferable. Examples of non-conjugated dienes include 1,
Chain-like non-conjugated dienes such as 4-hexadiene and 1,6-octadiene; cyclic non-conjugated dienes such as 1,4-cyclohexadiene, dicyclopentadiene, 5-vinylnorbornene and 5-ethylidene-2-norbornene; 2 , 3-
Trienes such as diisopropylidene-5-norbornene and 2-ethylidene-3-isopropylidene-5-norbornene may be mentioned, among which 1,4-hexadiene,
Dicyclopentadiene and 5-ethylidene-2-norbornene are preferred. As the ethylene-α-olefin copolymer rubber, it is possible to use two or more of them.

A rubber composition obtained by dynamically heat-treating the ethylene-α-olefin copolymer rubber itself or a mixture of the copolymer rubber and polypropylene in the presence of an organic peroxide and a crosslinking aid is also suitable. Can be used.

A preferred example of the ethylene-α-olefin copolymer rubber composition is a mixture of a propylene homopolymer and an ethylene-α-olefin copolymer, an organic peroxide and a crosslinking aid. A rubber composition that has been dynamically heat-treated in the presence of

The propylene homopolymer having a melt index (MI) of 11 to 30 g / 10 min is preferably used, and more preferably 12 to 20 g / 10 m.
in. If the MI is less than 11 g / 10 min, the fluidity of the composition will decrease. If it exceeds 30 g / 10 min, mechanical properties are deteriorated.

The ethylene-α-olefin copolymer rubber has a Mooney viscosity of 100 ° C. (ML _{1 + 4} 100 ° C.).
Those having a ratio of 10 to 100, preferably 20 to 80 are suitably used. When the Mooney viscosity at 100 ° C. is less than 10, mechanical properties are inferior, and when it exceeds 100, fluidity is inferior, resulting in poor appearance of the injection-molded product. Also, ethylene-α
-The ethylene content of the olefin copolymer rubber is 90-4.
0% by weight, the α-olefin content is 10 to 60% by weight, and the non-conjugated diene content is 0 to 12% by weight. When the ethylene content is 90% by weight or more, the ethylene component is increased, so that the copolymer rubber exhibits crystallinity, and as a result, the low temperature impact resistance is lowered. If it is less than 40% by weight, the decomposition reaction by the organic peroxide proceeds too much, resulting in deterioration of mechanical properties and poor appearance of the molded product. The ethylene content is preferably 80-45% by weight. When the content of non-conjugated diene is 12% by weight or more, it becomes difficult to control the crosslinking reaction.

100% by weight of a mixture consisting of a propylene homopolymer and an ethylene-α-olefin copolymer rubber
The proportion of the ethylene-α-olefin copolymer rubber in the rubber is 50 to 90% by weight, preferably 60 to 80% by weight.
Is. If it is less than 50% by weight, the crosslinking reaction by the organic peroxide does not proceed sufficiently and the mechanical properties are not improved. If it exceeds 90% by weight, thermoplastic properties are difficult to develop.

Examples of organic peroxides include 2,5-
Dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,1,3-bis (t-butylperoxyisopropyl) ) Benzene, 1,1-di (t-butylperoxy) -3,5,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (peroxybenzoyl) hexyne-3, and dicumyl peroxide Although there is no particular limitation, it can be appropriately selected depending on the melt-kneading conditions. The addition ratio of the organic peroxide is (a) +
(B) It can be selected in the range of 0.02 to 1.0 part by weight with respect to 100% by weight. If it is less than 0.02% by weight, the effect of the crosslinking reaction is small, and if it exceeds 1.0% by weight,
It is difficult to control the crosslinking reaction.

As the crosslinking aid, a bismaleimide compound such as N, N'-m-phenylene bismaleimide,
Further, polyfunctional compounds such as toluylene bismaleimide, p-quinonedioxymium, nitrobenzene, diphenylguanidine, trimethylolpropane, and ethylene glycol dimethacrylate can be used. N,
As N'-m-phenylene bismaleimide, for example, commercially available Sumifine BM (manufactured by Sumitomo Chemical Co., Ltd.), HVA-2 (manufactured by DuPont), or the like can be used. The addition ratio is 0.01 to 100% by weight of (a) + (b).
It can be selected in the range of 5.0% by weight. If it is less than 0.01% by weight, the effect on cross-linking is difficult to be exhibited, and if it exceeds 5.0% by weight, moldability is poor. Preferably 0.05
Is about 2.0% by weight.

As a method for dynamically heat-treating the propylene homopolymer (a) and the olefinic copolymer rubber (b), a mixing roll, a Banbury mixer, a twin-screw kneading extrusion method is used at a temperature range of 160 to 280 ° C. Melt kneading can be carried out by a known kneading device such as a machine, a kneader, and a continuous mixer. In this case, it is more desirable to carry out in an inert gas such as nitrogen or carbon dioxide.

In the present invention, the method of uniformly mixing the polypropylene (A) and the ethylene-α-olefin copolymer rubber and / or the rubber composition (B) is also the case of the above (a) and (b). Similarly to the above, melt kneading can be performed with a known kneading machine. Incidentally, in carrying out the present invention, kneading may be carried out in two stages,
It is also possible to use a multi-stage feed type twin-screw kneader to perform one step.

The inorganic filler (C) used in the present invention may be any one that improves rigidity and heat resistance, and examples thereof include calcium carbonate, barium sulfate, mica, crystalline calcium silicate, talc and Examples of the glass fiber include talc and glass fiber. The talc preferably has an average particle size of 1 to 5 μm. If the average particle size is less than 1 μm, problems such as re-aggregation and poor dispersion occur. Further, when the average particle size is 5 μm or more, there is little effect on improving impact resistance and rigidity. As the glass fiber, a surface treatment with a silane coupling agent, a fiber diameter of 4 to 13 μm
Chopped glass is used.

In the present invention, when the inorganic filler (C) is mixed, the above-mentioned kneading equipment can be used in the same manner, and a mixture of (A) and (B) is obtained in advance and then (C) is mixed. Or a method of simultaneously mixing (C) when mixing (A) and (B).
Usually, a method of simultaneously adding (A), (B) and (C) and mixing is used.

The contents of (A), (B) and (C) in the final composition are 20 to 95% by weight, 5 to 40% by weight and 0, respectively.
-40% by weight, preferably 55-85% by weight, 10-30% by weight, and 0-25% by weight, respectively. If the rubber and / or the rubber composition (B) is less than 5% by weight, the impact resistance will be poor, and if it exceeds 40% by weight, the fluidity will be deteriorated and the appearance of the molded product will be poor. Further, if the inorganic filler (C) exceeds 40% by weight, the fluidity decreases.

The polypropylene resin composition of the present invention further contains a heat-resistant stabilizer, a nucleating agent, an ultraviolet absorber, a lubricant, an antistatic agent, a flame retardant, and a flame-retardant, within the range not impairing the object of the present invention.
It may contain pigments, dyes, other polymers and the like.

[0023]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. The methods of measuring physical properties and the specifications of the kneading equipment used in the examples are as follows. (1) Wide-angle X-ray diffraction measurement A sample obtained by granulating and kneading was compression molded (230 ° C
・ 30 kg / cm ² · 5 minutes, 30 ° C · 30 kg / cm ²
A 1 mm press sheet was prepared as a test piece for 5 minutes. RU-200B manufactured by Rigaku Corporation is used as a device, and C
u tube, 40kV ・ 30mA, slit (DS = 1m
m, RS = 0.15 mm, SS = 1 mm), line focus, monochromator used, scan speed = 1 ° /
The measurement from 2θ = 5 ° to 35 ° was performed under the condition of min. (2) Melt index The melt index was determined by the method specified in JIS-K-6758.
The measurement temperature was 230 ° C. and the load was 2.16 kg. (3) Bending test According to the method specified in JIS-K-7203. Using a test piece (thickness 6.4 mm) molded by injection molding, the flexural modulus was evaluated under the conditions of a span length of 100 mm and a load speed of 2.0 mm / min. The measurement temperature was 23 ° C. (4) Izod Impact Strength (Izod Impact) The method was defined in JIS-K-7110. Using a test piece (thickness: 6.4 mm) molded by injection molding, notch processing was performed after molding, and the notched impact strength was evaluated. The measurement temperature was 23 ° C. unless otherwise specified. For other temperatures, the measurement was carried out after the condition was adjusted for 2 hours in a constant temperature bath. (5) Heat distortion temperature (HDT) According to the method specified in JIS-K-7207. Using a test piece (thickness: 6.4 mm) molded by injection molding, with a fiber stress of 4.6 kgf / cm ² , 2 ° C.
The temperature at which the test piece had a deflection of 0.254 mm when heated at a heating rate of / min was measured. (6) Rockwell hardness According to the method specified in JIS-K-7202. Using a test piece (two sheets having a thickness of 3.2 mm stacked) formed by injection molding, the steel ball was evaluated using R, and the value was displayed on the R scale. (7) Banbury mixer Kobe Steel MIXTRON BB-16 MIXE
An R, 2 wing type rotor having a chamber volume of 17.7 liters was used. (8) Biaxial Kneading Extruder A TEX-44SS-30W-2V (different rotation type) manufactured by Nippon Steel Co., Ltd. and a screw 44 mm × 30 L / D were used.

In the following Examples and Comparative Examples, various materials use the abbreviations shown in Tables 1 and 2, that is, the following. PP: Propylene homopolymer BC: Ethylene-propylene block polymer EPR: Ethylene-propylene copolymer rubber EPDM: Ethylene-propylene-non-conjugated diene terpolymer rubber TALC: Talc PO: Organic peroxide 2,5 -Dimethyl-2,5-di (t-butylperoxy) hexane BM: Cross-linking aid N, N'-m-phenylene bismaleimide

Reference Example: Preparation of Masterbatch (MB) 70% by weight of ethylene-propylene-non-conjugated diene terpolymer rubber (EPDM) as rubber and 30% by weight of propylene homopolymer (PP-3) as polypropylene. %
And 0.1% by weight of organic peroxide (PO) and 0.5% by weight of crosslinking aid (BM) in a Banbury mixer in an adiabatic state for 10 minutes, and then passed through a roll. A sheet cutter was used to make pellets (hereinafter referred to as MB).

Example 1 As polypropylene, a propylene homopolymer (PP-
1) 44% by weight, ethylene-propylene block copolymer (BC) 36% by weight, and MB prepared in Reference Example 20% by weight were uniformly mixed with various stabilizers, and then mixed in a twin-screw kneading extruder. Granulation at 200 ° C., and a test piece was prepared by an injection molding machine and evaluated. Table 1 shows the physical properties of PP-1 and BC.
Table 2 shows the composition of the mixture, and Table 3 shows the evaluation results.

Comparative Examples 1, 3 and 4 In Comparative Example 1, 71% by weight of PP-2 and 29% by weight of MB,
In Comparative Example 3, BC is 100% by weight, and in Comparative Example 4, MB is ethylene-propylene copolymer rubber (EP.
R), and test pieces were prepared and evaluated in the same manner as in Example 1. Table 3 shows the results.

Example 2 34% by weight of PP-1, 36% by weight of BC and 20% of MB
A test piece was prepared and evaluated in the same manner as in Example 1 except that the weight% and the talc (TALC) were 10% by weight. Table 3 shows the results.

Comparative Example 5 A test piece was prepared and evaluated in the same manner as in Example 1 except that MB was changed to EPR in Example 2. Table 3 shows the results.

Example 3 24% by weight of PP-1, 36% by weight of BC and 20% of MB
Test pieces were prepared and evaluated in the same manner as in Example 1 except that the weight% and the talc (TALC) were 20% by weight. Table 3 shows the results.

Comparative Examples 2 and 6 Comparative Example 2 was 51% by weight of PP-2, 29% by weight of MB and 20% by weight of TALC, and Comparative Example 6 was the same as Example 3 except that MB was changed to EPR. Test pieces were prepared and evaluated in the same manner as in Example 1. Table 3 shows the results.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

According to the present invention, a polypropylene resin composition comprising a specific polypropylene and a specific rubber composition, or a polypropylene resin composition comprising a specific polypropylene, a specific rubber composition and an inorganic filler is provided. Provided. Such compositions have mechanical properties, especially rigidity,
It has excellent heat resistance and impact resistance, and can be used as a material suitable for, for example, molded articles for automobile parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Haruyuki Suzuki Inventor Haruyuki Suzuki 1-5 Anezaki Kaigan, Ichihara, Chiba Sumitomo Chemical Co., Ltd. (72) Yuichi Miyake 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Takao Nomura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Takesumi Nishio 1 Toyota Town, Toyota City, Aichi Toyota Motor Co., Ltd.

Claims (1)

[Claims] 1. A polypropylene (A) comprising the following (i) and / or (ii): 20 to 95% by weight, and (i)
The crystallite size calculated from the full width at half maximum of the diffraction peak showing the (040) plane obtained by wide-angle X-ray diffraction measurement is 280.
A propylene homopolymer having a size of A or more (ii) A fine crystal size calculated from the half width of the diffraction peak showing the (040) plane obtained by wide-angle X-ray diffraction measurement of the propylene homopolymer part of the first segment is 280 A or more. Ethylene-propylene block copolymer (2) The following ethylene-α-olefin copolymer rubber and / or rubber composition (B): 5 to 40% by weight, when kneaded with polypropylene (A), The crystallite size calculated from the full width at half maximum of the diffraction peak showing the (040) plane obtained by the wide-angle X-ray diffraction measurement of the kneaded product does not decrease by 5% or more than the crystallite size of the polypropylene (A) ethylene- α-olefin copolymer rubber and /
Or a rubber composition (3) an inorganic filler (C): 0 to 40% by weight, and a polypropylene resin composition.