JPS646657B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyolefin composition, and more particularly, it is composed of high-density polyethylene, crystalline polypropylene, ethylene-α-olefin copolymer rubber, and filler, and has excellent heat deformation resistance, surface hardness, and rigidity, and particularly has excellent drawdown resistance. The present invention relates to a polyolefin composition with good properties and suitable for large-scale blow molding. Conventionally, polyethylene and polypropylene are both relatively inexpensive and have good moldability, so they have been used as general-purpose resins as molded products in a wide range of fields such as films, sheets, containers, electromechanical parts, and miscellaneous goods. In addition, extrusion, injection, and blow molding methods are used for molding, but for particularly large blow molded products, polyethylene, especially high-density polyethylene, is used, which has better drawdown resistance than polypropylene. is being done a lot. However, among large blow molded products, structural members that are exposed to sunlight, such as automobile exterior parts, bumpers, pallets, solar water heater heat collectors, etc., do not have sufficient heat resistance to denaturation with polyethylene molded products alone. There were also limits in terms of surface hardness and rigidity. The present invention was made for the purpose of improving the drawbacks of polyethylene in large blow molded products as described above, and the polyolefin composition of the present invention has the following characteristics: (a) Melt index (temperature 190°C, load High-density polyethylene 50 (measured under 2.16Kg conditions, hereinafter referred to as MI) of 0.5g/10 minutes or less
~93% by weight, (b) 5 to 50% by weight of crystalline polypropylene with 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 g/10 minutes or less, ( c) 2 to less than 20% by weight of an ethylene-α-olefin copolymer rubber having a melt flow index of 1.0 g/10 minutes or less, and (d) 0 to 30% by weight of a filler. Hereinafter, the configuration of the present invention will be explained in detail. The high-density polyethylene used in the present invention has a density of 0.93 g/cc or more, preferably 0.94 to
0.97 g/cc, weight average molecular weight is 100,000 or more, preferably 150,000 or more, and MI is 0.5 g/10 min or less, preferably 0.3 g/10 min or less, particularly preferably 0.1 g/10 min or less.
It can take less than 10 minutes. If MI is outside these ranges, the drawdown resistance decreases, making it difficult to make the thickness distribution of the resulting molded product uniform, and impact resistance decreases, which is not preferable. In addition to the homo-type high-density polyethylene, a type copolymerized with a comonomer such as butene-1, hexene-1, etc. can also be used. In general, the former is used to improve rigidity, and the latter to prevent stress cracking, respectively. 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 is 0.5g/10 minutes or less.
If the MFI exceeds 0.5 g/10 minutes, 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). Among these, ethylene-propylene copolymer rubber (hereinafter referred to as EPR) or EPDM is preferred. These ethylene-α-
Olefin copolymer rubber has an ethylene content of 20
~90% by weight, Mooney viscosity (JISK)
6300ML ₁₊₄ 100°C or lower) is preferably 60 to 100, particularly MFI is 1.0 g/10 minutes or less, preferably 0.7 g/10 minutes or less. If the ethylene content in the copolymer rubber exceeds 90% by weight, the rubber properties will be insufficient and the impact strength of the resulting molded product will be reduced. In addition, if the Mooney viscosity of the copolymer rubber is outside the above range, the compatibility during kneading of high density polyethylene and crystalline polypropylene, which will be described later, will be poor, and the drawdown resistance of the composition will deteriorate. It is also undesirable. Examples of fillers used in the present invention include mica, talc, fibrous calcium silicate, calcium carbonate, barium sulfate, kaolin,
Examples include alumina, magnesium carbonate, titanium oxide, silica, carbon black, glass fiber, and carbon fiber. The particle size of these fillers is from 0.05 to
200μ, 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 polyolefin composition of the present invention comprises 50 to 93% by weight of the above-mentioned high-density polyethylene, 5 to 50% by weight of crystalline polypropylene, 2 to less than 20% by weight of ethylene-α-olefin copolymer rubber, and 0 to 30% of filler.
% by weight. If the proportion of crystalline polypropylene in the resin composition is less than 5% by weight, the heat resistance of the resulting molded product will not be improved, while if it exceeds 50% by weight, drawdown resistance and impact resistance will deteriorate and large It becomes difficult to mold the blow molded product. Furthermore, if the proportion of the ethylene-α-olefin copolymer rubber is less than 2% by weight, the compatibility between high-density polyethylene and crystalline polypropylene is insufficient, resulting in poor impact resistance and surface smoothness. If the weight exceeds the weight, the rigidity, heat resistance, surface hardness, etc. of the molded product obtained will decrease. Further, if the proportion of the filler exceeds 30% by weight, although heat resistance, surface hardness and rigidity are improved, it is not preferable because the fusion of the cut portion of the parison during blow molding deteriorates and the impact resistance decreases. 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, a Banbury mixer, a continuous kneader, or a single-screw or twin-screw extruder. 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, antioxidants, ultraviolet absorbers, stabilizers such as metal deterioration inhibitors, lubricants, antistatic agents, electrical property improvers, flame retardants, processability improvers, pigments, etc. Various additives can be blended. As described above, the polyolefin 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 excellent drawdown resistance, and the molded products obtained have excellent heat resistance, surface hardness, rigidity, etc. without impairing impact resistance. It is suitable as a composition for large-scale blow molding of products, solar water heater heat collectors, pallet fuel tanks, etc. Particularly when blow molding is performed, a coating film with excellent strength can be obtained. 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) Flexural modulus ASTM D790 (2) Izot impact strength
ASTM D256 3.2mm thick test piece, with notch (3) Surface hardness ASTM D785 (Rockwell hardness) (4) Heat distortion temperature JIS K7207 Load 4.6Kg/cm ² (5) Drawdown evaluation Large blow molding machine [Ishikawajima Harima Manufactured by Heavy Industries, IPB-200C (product name)]
A bumper with a length of 1.6 m, a width of 0.16 m, and a weight of 3 kg and a length of 0.4 m and a width of 0.3
Molding a fuel tank of m, the ratio of the upper wall thickness to the lower wall thickness is 0.8 ~ 1.0, ◎, 0.6 ~ 0.8
Less than 0.6 was rated as 〇, less than 0.6 was rated as poor molding or non-moldable was rated as ×. Examples 1 to 8 High density polyethylene (density 0.950 g/cc,
MI 0.04 g/10 min, hereinafter referred to as HDPE-1), crystalline polypropylene (MFI 0.5 g/10 min, hereinafter referred to as PP), EPDM (ethylene content 72%, Mooney viscosity 90, MFI 0.7 g/10 min), EPR (ethylene content 73%, Mooney viscosity 70, MFI 0.7g/10 min), talc (average particle size 5μ), calcium carbonate (average particle size
5μ), fibrous crystalline calcium silicate (trade name: wollastenite, average particle size 10μ), and alumina (average particle size 0.1μ) were blended in the combinations shown in Table 1 and mixed in a high-speed mixer. Temperature the mixture
The mixture was melt-kneaded in a continuous kneader set at 200°C and then pelletized. The obtained pellets were blow molded to evaluate the drawdown, and test pieces were molded using an injection molding machine to measure the flexural modulus, thermal deformation temperature, and Izo impact strength.The results are shown in Table 1. Indicated. In Example 8, the coating film strength was further determined to be 720 g/10 mm, but
In the case of HDPE alone used in Example 8, 60g/10
It was only mm.

【table】

[Table] Comparative Examples 1 to 3 In the examples, when PP with an MFI of 2 g/10 min was blended (Comparative Example 1), when the blended amount of talc exceeded 30% (Comparative Example 2), and
When the EPDM content exceeds 30% (Comparative Example 3)
A similar evaluation was conducted for , and the results are shown in Table 2.
It was shown to.

[Table] Examples 9 and 10 The same procedure was repeated as in Examples 2 and 3 except that high-density polyethylene (hereinafter referred to as HDPE-2) with a density of 0.953 g/cc and an MI of 0.3 g/10 minutes was used instead of HDPE-1. The results are shown in Table 3. Comparative Example 4 In Example 2, density was used instead of HDPE-1.
Evaluations were conducted in the same manner except that high-density polyethylene of 0.950 g/cc and MI of 0.6 g/10 min was used, and the results are also listed in Table 3.

[Table] Examples 11-13 High-density polyethylene (density 0.950 g/cc,
MI0.05g/10min, hereinafter referred to as HDPE), crystalline polypropylene (MFI0.4g/10min, hereinafter referred to as PP), EPR (ethylene content 73%, Mooney viscosity
70) and mica (average particle size 30μ) in Table 4.
Combine the combinations shown in and mix with a high-speed mixer.
The resulting mixture was melt-kneaded in a continuous kneader set at a temperature of 200°C and then pelletized. Blow molding was performed using the obtained pellets to evaluate drawdown, and test pieces were molded using an injection molding machine.
The flexural modulus, Izot impact strength, surface hardness, and heat distortion temperature were measured, and the results are shown in Table 4.

【table】

【table】

Claims (1)

[Claims] 1 (a) 50-93% by weight of high-density polyethylene with a melt flow index of 0.5 g/10 minutes or less, (b) 5-50% by weight of crystalline polypropylene with a melt flow index of 0.5 g/10 minutes or less, and ) A polyolefin composition comprising 2 to less than 20% by weight of an ethylene-α-olefin copolymer rubber having a melt flow index of 1.0 or less.