JPH0242852B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a polypropylene resin composition having high rigidity and high impact resistance. More specifically, a) an ethylene-propylene block copolymer and b) a specified ethylene-
c) for 100 parts by weight of a resin composition consisting of a propylene copolymer rubber (hereinafter abbreviated as EPM) and a specified ethylene-propylene-diene terpolymer rubber (hereinafter abbreviated as EPDM).
By adding 1 to 30 parts by weight of talc having a particle size of 3 μm or less, a polypropylene resin having the above-mentioned properties is provided. [Prior art] Currently, polypropylene resin is widely used because it has a light weight, high rigidity, and excellent heat resistance and chemical resistance. It had poor properties and was unsuitable for use at low temperatures. For this reason, impact-resistant grades based on copolymerization of ethylene and propylene have been developed and put on the market, but recently the required performance has become increasingly sophisticated, and there are cases where impact resistance comparable to that of impact-resistant grades is no longer satisfactory. In such cases, a method is generally used in which an impact resistance modifier such as rubber is added to improve the impact resistance. However, a resin composition to which such an impact modifier such as rubber is added has improved impact resistance, but on the other hand, rigidity and heat resistance are extremely reduced. For example, in fields such as cushioning materials, bumpers, and soft hoses, resins with conflicting performances such as high rigidity and high heat resistance as well as high impact resistance are required. It has been difficult to obtain a resin composition having these required performances using the method of adding materials. Further, in order to improve the rigidity of polypropylene resin, a method of adding an inorganic filler is widely used. It is known that in this method, as the proportion of inorganic filler added increases, the rigidity and heat resistance are improved, but on the other hand, the impact resistance is significantly reduced. For example, Industrial Materials VoI20, No.
7, p. 29 (1972) shows that as the amount of talc added to polypropylene increases, the rigidity and heat distortion temperature improve, but the Izod impact strength decreases. Also plastic VoI17, No.12,
On page 27 (1966), diatomaceous earth is added to polypropylene.
It has been shown that the Izod impact strength similarly decreases when calcium carbonate, talc, and asbestos are added. However, the inorganic fillers used in these methods are extremely common, and no attention is paid to particle size or the like. In particular, when molding a large molded product such as a bumper, there was a problem in that even if sufficient impact strength was obtained with a small test piece, the practical physical properties were not sufficiently strong. [Problems to be Solved by the Invention] An object of the present invention is to provide a polypropylene resin composition that has high rigidity and high impact resistance, particularly impact resistance at low temperatures. [Means and effects for solving the problem] In order to improve the rigidity and impact resistance of polypropylene resin, the present inventors have developed an inorganic filler and an impact resistance modifier such as EPM or EPDM. We have tried various methods of using both at the same time, but with commonly used inorganic fillers with a particle size of 5 μm to 150 μm, the impact resistance decreases as the amount of inorganic filler added increases, as in the example shown above. Therefore, it was not possible to simultaneously improve rigidity and impact resistance. The present inventors further conducted intensive studies to develop a polypropylene resin composition that has both high rigidity and high impact resistance. The present invention was achieved by discovering the surprising fact that rigidity and impact resistance are significantly improved by using a specific amount of talc in combination with talc. That is, the present invention provides (a) ethylene-propylene block copolymer 95
~50% by weight and (b) an ethylene-propylene copolymer rubber having a propylene content of 20 to 50% by weight and a Mooney viscosity at 100°C (ML100°C 1-4) of 20 to 100 and a propylene content of 20 to 50% by weight. An ethylene-propylene-diene ternary copolymer having a Mooney viscosity of 20 to 110 at 100°C at 50% by weight, and in which the diene as the third component is one of ethylidenenorbornene, dicyclopentadiene, and 1,4-hexadiene. Resin composition 100 consisting of 5-50% by weight of polymer rubber
A polypropylene resin composition comprising: (c) 1 to 30 parts by weight of talc having a particle size of 3 μm or less, based on the weight part. The polypropylene resin used in the present invention is an ethylene-propylene block copolymer, and preferably has a melt flow index (hereinafter abbreviated as MI) of 5 g/10 min or more at 230°C. If an MI of less than 5 g/10 min is used, the resulting resin composition will have poor fluidity and poor appearance. Furthermore, the use of polypropylene homopolymers or random copolymers with ethylene is undesirable because impact resistance, especially at low temperatures, decreases. Used in the present invention. EPM is limited to propylene content of 20-50% by weight and Mooney viscosity of 20-100 at 100℃, and EPDM
The propylene content is 20 to 50% by weight, the Mooney viscosity at 100°C is 20 to 110, and the third component diene is ethylidene norbornene, dicyclopentadiene, or 1,4-hexadiene. limited to. This limitation applies to the EPM
The low glass transition temperature (hereinafter abbreviated as HTg) of EPDM is effective for improving the impact resistance of polypropylene resins, and the EPM used
and due to the existence of an optimal range for the molecular weight of EPDM. When attempting to improve impact resistance by adding EPM and EPDM to polypropylene resin,
It is necessary that the EPM and EPDM used have a low Tg. It is known that the Tg of EPM and EPDM is minimal in the range of propylene concentrations of 15 to 40 moles, which corresponds to a range of 20 to 50 moles of propylene. Furthermore, when trying to improve the impact resistance of a resin by adding rubber, it is known that there is an optimum value for the dispersed particle size of the rubber, but even in systems of polypropylene resin, EPM, and EPDM, There is an optimal value. If the molecular weight of EPM and EPDM is too small, the dispersed particle size will be smaller than the optimum value, and if the molecular weight of EPM and EPDM is too large, the dispersed particle size will be larger than the optimum value, which is not preferable. The optimum molecular weight of EPM and EPDM is expressed as Mooney viscosity, which is correlated with molecular weight.
100, and ranges from 20 to 110 for EPDM. The addition ratio of EPM and EPDM in the present invention is in the range of 5 to 50% by weight, and it is necessary to use both in combination, and the usage ratio of each is 1:10 to 10:
It can be appropriately determined within the range of 1. If the amount of EPM and EPDM added is less than 5% by weight, the effect of improving impact resistance will be small, and if it exceeds 50% by weight, the resulting resin composition will have low rigidity, which is not preferable in either case. From the standpoint of low-temperature impact of the molded product obtained, it is practically preferable to use EPM and EPDM together in an amount of 5% by weight or more each. In the method of the present invention, by using EPM and EPDM in combination at 5% by weight or more each, the strength in a practical impact test at -40°C is significantly improved. The inorganic filler used in the present invention is limited to talc. Inorganic fillers other than talc, such as calcium carbonate and barium sulfate, are less effective in improving rigidity than talc, and are also less effective in improving heat resistance. When a product using calcium silicate is molded, flashing occurs due to moisture content, both of which are undesirable. Furthermore, it is essential that the particle size of the talc used in the present invention is 3 μm or less, particularly 2 μm or less.
It is preferable that it is below m. If talc with a particle size exceeding 3 μm is used, the impact resistance of the resulting polypropylene resin composition will decrease. Here, the particle size of talc in the present invention is an equal area diameter determined by a light transmission method, and the measurement is carried out using, for example, a light transmission particle size distribution analyzer manufactured by Seishin Enterprise Co., Ltd.
Using SKC2000 or the like, the value determined as the particle size at 50% of the particle size cumulative distribution (generally referred to as D ₅₀ ) is used. In the present invention, the addition ratio of talc with a particle size of 3 μm or less is that of polypropylene resin and EPM.
1 to 100 parts by weight of a resin composition made of EPDM
The amount ranges from 30 parts by weight, preferably from 3 to 20 parts by weight. When the proportion of talc added is less than 1 part by weight, the stiffness improvement effect is small, and when it exceeds 30 parts by weight, the stiffness of the resulting resin composition is significantly improved, but on the other hand, the impact resistance and tensile properties are decreased, which is not preferable. . In the composition of the present invention, stabilizers against oxygen, heat and light, metal deterioration inhibitors, lubricants, etc. that are commonly used in polypropylene resins may be added. The resin composition of the present invention is usually obtained by premixing the components in a Henschel mixer or the like, then melt-kneading them in a single-screw or twin-screw extruder to form pellets, and extrusion using the pellets. It can be formed into a product by a molding method such as molding, injection molding, rotational molding, or compression molding. [Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. Examples 1 to 6 The polypropylene resin was an ethylene-propylene block copolymer manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name BJ4H (MI = 20 g/10 min), the EPM had a propylene content of 27% by weight, and a Mooney viscosity of 21 at 100°C. Tafmer P0280, a trade name manufactured by Mitsui Petrochemical Co., Ltd., EP25X, a trade name of Japan EP Rubber Co., Ltd., which has a propylene content of 37% by weight as EPDM, a Mooney viscosity of 90 at 100°C, and the third component is ethylidene norbornene, is an inorganic filler. As particle size 1.3μm
and 1.8 μm talc were blended in the proportions shown in Table 1, mixed in a Henschel mixer, and then pelletized in an extruder. Using this pellet, test pieces were molded using an injection molding machine, and performance evaluation was performed. The flexural modulus was measured in accordance with ASTM-D-790, and the Izot impact strength was measured in accordance with ASTM-D-256 at temperatures of -30°C and -40°C. Further, as an evaluation of heat resistance, the heat distortion temperature was measured according to ASTM-D-648. In addition, as a practical impact test of the product, the molded products shown in Figures 1, 2 and 3 were injection molded (molding conditions: molding machine/Nippon Doso N-400B, molding temperature/230℃, injection pressure 850Kg/cm ² ). After leaving the molded product in a constant temperature room at -40°C for more than 2 hours, a 3.26 kg copper ball was dropped onto the top of the molded product, and the height at which the molded product would break was determined. The appearance of the above molded product was also evaluated. Comparative Examples 1 to 5 In Example 1, talc with particle sizes of 3.3 μm, 5.5 μm, and 7.2 μm was used instead of talc with particle size of 1.3 μm.
Table 1 shows the results obtained by testing in the same manner as in Example 1. Comparative Example 6 Table 1 shows the results obtained by blending and testing in the same manner as in Example 1 except that talc was not added. Comparative Examples 7 to 9 In Example 1, barium sulfate with a particle size of 1.2 μm, calcium carbonate with a particle size of 1.9 μm, and calcium silicate with a particle size of 1.0 μm were used in the proportions shown in Table 2 instead of talc with a particle size of 1.3 μm. The results obtained by blending and testing in the same manner as in Example 1 are shown in Table 2. Comparative Examples 10, 11 Ethylene-propylene block copolymer trade name BJ4H (MI = 20 g/10 min) manufactured by Mitsui Toatsu Chemical Co., Ltd. is used as the polypropylene resin, propylene content is 20% by weight as EPM, and Mooney viscosity at 100°C is 70. Product name manufactured by Japan EP Rubber Co., Ltd.
EP07P, a propylene content of 28% by weight, a Mooney viscosity of 88 at 100°C, and a third component of ethylidene norbornene, EPDM brand name EP57P from EP Rubber Co., Ltd., were used in the proportions shown in Table 2.
Table 2 shows the results obtained by testing in the same manner as in Example 1.
It was shown to. Comparative Example 12 In Example 1, instead of BJ4H, propylene homopolymer manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name
The test was conducted in the same manner as in Example 1 except that J3H (MI=12g/10min) was used, and the results are shown in Table 2.

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〔Effect of the invention〕

The polypropylene resin composition according to the present invention has high rigidity and high impact resistance, particularly low-temperature impact resistance, so that it is used in a wide range of applications and is industrially useful.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a test molded product used in a practical impact test of a product using a polypropylene resin composition, and FIG. 2 is a cross-sectional view thereof.

Claims (1)

[Scope of Claims] 1 (a) ethylene-propylene block copolymer 95 to 50% by weight; and (b) propylene content of 20 to 50% by weight, and a Mooney viscosity at 100°C (ML100°C 1+4) of 20 ~100 and a propylene content of 20 to 50% by weight and a Mooney viscosity of 20 to 110 at 100°C, and the third component diene is ethylidenenorbornene, dicyclopentadiene, 1 , 4-hexadiene resin composition 100 consisting of 5 to 50% by weight of ethylene-propylene-diene terpolymer rubber
A polypropylene resin composition comprising: (c) 1 to 30 parts by weight of talc having a particle size of 3 μm or less, based on the weight part.