JPS646656B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polypropylene composition, in particular, a large-sized blow molding composition comprising crystalline polypropylene, ethylene-α-olefin copolymer rubber, and a filler, which has excellent rigidity and impact resistance, and in particular has good drawdown resistance. The invention relates to polypropylene compositions suitable for. Conventionally, polypropylene has been used for molded products for various purposes due to its low specific gravity, high rigidity, and excellent heat resistance and chemical resistance, and various molding methods such as injection, extrusion, blowing, and pressing have been applied. ing.
However, among these molding methods, blow molding has poor drawdown resistance compared to high-density polyethylene, which has relatively similar physical properties, and tends to cause uneven thickness in molded products, which limits its application, especially in large-scale blow molding. The drawback was that it was not suitable for molding. In addition, polypropylene has a lower impact strength at low temperatures than polyethylene, which limits its field of application. The present invention has been made for the purpose of improving the above-mentioned drawbacks and obtaining a polypropylene composition that has good drawdown resistance in blow molding and has excellent impact resistance without losing rigidity. The polypropylene composition has (a) a melt flow index (measured according to JISK 6758 at a temperature of 230°C and a load of 2.16 kg, hereinafter referred to as MFI) of 0.5.
50-95% by weight of crystalline polypropylene less than g/10 min, (b) MFI less than 1.0 g/10 min, ethylene content 20
~90% by weight, ethylene with Mooney viscosity 60-100
5 to 30% by weight of α-olefin copolymer rubber and (c) 0 to 30% by weight of filler, and the melt flow index of the composition is 0.5 g/10 minutes or less. Yes, used exclusively for blow molding. Hereinafter, the configuration of the present invention will be explained in detail. The crystalline polypropylene used in the present invention is isotactic crystalline polypropylene, and may be a propylene homopolymer or a propylene-ethylene random or block copolymer with an ethylene content of 10 mol% or less, MFI less than 0.5g/10min, preferably 0.4
g/10 minutes or less. If the MFI is 0.5 g/10 minutes or more, the drawdown during blow molding will be severe, making it difficult to mold a large blow molded product with a long parison. The ethylene-α-olefin copolymer rubber used in the present invention is a copolymer rubber of ethylene and α-olefin, such as propylene, butene-1, hexene-1, octene-1, etc., or an ethylene-propylene based copolymer rubber. and non-conjugated dienes, such as ethylidene norbornene, as a third component.
Ternary copolymer rubber (hereinafter referred to as
EPDM), etc. Among these, ethylene-propylene copolymer rubber (hereinafter referred to as EPR)
Or EPDM is preferred. These ethylene-α
-MFI of olefin copolymer rubber is 1.0g/10
minutes or less, preferably 0.7 g/10 minutes or less, with an ethylene content of 20 to 90% by weight and a Mooney viscosity (JISK-6300ML ₁₊₄ 100℃, hereinafter the same) of 60 to 90%.
100 is preferred. If the MFI of the copolymer rubber exceeds 1.0 g/10 minutes, the drawdown resistance will deteriorate. Furthermore, if the ethylene content exceeds 90% by weight, the rubber properties will be insufficient and the impact strength of the resulting molded product will be reduced.
Furthermore, if the Mooney viscosity is low outside the above range, the drawdown resistance will be poor, while if it is high, the rigidity of the molded product obtained will be reduced, both of which are undesirable. Examples of fillers used in the present invention include mica, talc, fibrous calcium silicate,
Calcium carbonate, barium sulfate, kaolin, alumina, magnesium carbonate, titanium oxide, silica,
Examples include carbon black, glass fiber, and carbon fiber. The particle size of these fillers is 0.05~200μ
The thickness is preferably 0.1 to 100μ. Further, the filler can be surface-treated with various organic silane compounds in order to improve its affinity with polyolefin. The type, particle size, and amount of the filler to be added are appropriately selected depending on the required shape and mechanical properties of the molded article. The polypropylene composition of the present invention comprises 50 to 95% by weight of the above-mentioned crystalline polypropylene, ethylene-α-
The composition consists of 5-30% by weight of olefin copolymer rubber and 0-30% by weight of filler. If the proportion of the ethylene-α-olefin copolymer rubber in the composition is less than 5% by weight, the drawdown resistance and the impact resistance of the resulting molded product will not be improved;
On the other hand, if it exceeds 30% by weight, the drawdown resistance will deteriorate and the resulting molded product will have lower rigidity, heat resistance, etc. Furthermore, when the proportion of filler exceeds 30% by weight, heat resistance, surface hardness and rigidity improve;
This is undesirable because it worsens the fusion of the cut portion of the parison during blow molding and reduces impact resistance. Next, the method for producing the composition of the present invention involves blending the above-mentioned components and kneading them in a heated molten state using a kneading machine such as a high-speed mixer, Banbury mixer, continuous kneader, single-screw or twin-screw extruder, etc. obtained by The resulting composition preferably has an MFI of 0.5 g/10 minutes or less from the viewpoint of drawdown resistance. In addition, when blending and kneading each component, stabilizers such as antioxidants, ultraviolet absorbers, and metal deterioration inhibitors, lubricants, antistatic agents, electrical property improvers, flame retardants, processability improvers, pigments, Various additives such as crystal nucleating agents can be blended. As described above, the polypropylene composition of the present invention can be produced into containers, hollow objects, boards, sheets, spherical objects, rod-shaped objects, etc. by various molding methods such as blow molding, press molding, extrusion molding, and injection molding. Can be molded into various molded objects such as pipes. In addition, the composition of the present invention has good drawdown resistance, and the resulting molded products have excellent impact resistance, and those containing fillers have particularly excellent rigidity, heat resistance, and surface hardness, so they can be used for large blowdowns. It is suitable as a composition for molding molded articles such as bumpers, pallets, solar water heater heat collectors, etc. The present invention will be explained in more detail below using Examples. In addition, % in an example shows weight, and the test method is as follows. (1) Evaluation of drawdown Large-scale blow molding machine [manufactured by Ishikawajima Harima Heavy Industries Co., Ltd.
IPB-200C (product name)], length 1.6m,
A blow bumper with a width of 0.16 m and a weight of 3 kg is molded, and the ratio of the upper wall thickness to the lower wall thickness is 0.8 to 1.0.
◎, 0.6 to less than 0.8 as ○, less than 0.6, poor molding or unmoldability as ×. (2) Flexural modulus ASTM D790 (3) Izot impact strength ASTM D256 3.2 mm thick test piece, notched Examples 1 to 7 Crystalline polypropylene (hereinafter referred to as PP) with MFI of 0.35 g/10 min, EPDM (MFI 0.7 g/10 min, ethylene content 72%, Mooney viscosity 90), EPR
(MFI 0.7g/10min, ethylene content 73%, Mooney viscosity 70), mica (average particle size 100μ), talc (average particle size 5μ) and alumina (average particle size 0.1μ)
were blended in the combinations shown in Table 1 and mixed in a high-speed mixer, and the resulting mixture was melt-kneaded in a continuous kneader set at a temperature of 200°C and then pelletized. The obtained pellets were blow molded to evaluate drawdown, and test pieces were molded using an injection molding machine to measure the flexural modulus and Izot impact strength. The results are shown in Table 1. Examples 8 and 9 In Examples 1 and 2, the MFI was 0.35 g/10 min.
Evaluations were conducted in the same manner except that PP with an MFI of 0.25 g/10 minutes was used instead of PP, and the results are also listed in Table 1.

[Table] Comparative Examples 1 to 7 For comparison, the same PP as used in the example,
Using EPDM, talc, mica, and alumina, when PP is used alone (Comparative Example 1), when it is mixed in the proportions shown in Table 2 (Comparative Examples 2 to 5), and
Similar evaluations were conducted for the cases in which PP with MFI of 0.6 g/10 min and 1.0 g/10 min (Comparative Examples 6 and 7) were blended, and the results are shown in Table 2.

【table】

[Table] Comparative Examples 8 and 9 For comparison, the same as used in Example 1
A similar evaluation was conducted for a product containing PP (MFI 0.35 g/10 min, PP-1), EPDM, talc, mica, and a mixture of crystalline polypropylene (PP-2) with an MEI of 23 g/10 min. Display the results.
Shown in 3.

【table】

【table】

Claims (1)

[Claims] 1 (a) 50 to 95% by weight of crystalline polypropylene with a melt flow index of less than 0.5 g/10 min, and (b) a melt flow index of 1.0 g/10 min or less, ethylene content of 20 to 90 wt%, Moony viscosity 60
-100 ethylene-α-olefin copolymer rubber in an amount of 5 to 30% by weight, and the composition has a melt flow index of 0.5 g/10 minutes or less.