JPS6328462B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polypropylene composition suitable for highly rigid large-sized molded articles, and more specifically, the present invention relates to a polypropylene composition containing a crystalline ethylene-propylene block copolymer as a main component,
A polypropylene composition for large molded products that has particularly excellent rigidity and heat deformation resistance, has high impact strength, is lightweight and has a good appearance, and also has good moldability when molded into large molded products. It is about things. Traditionally, plastic industrial parts materials for home appliances, automobiles, etc. have been ABS, Noryl (modified PPO), ASG,
Polycarbonate etc. are used. However, these polymers have problems in either impact strength, rigidity, or moldability, and are not fully satisfactory as materials for plastic industrial parts. On the other hand, inorganic filler-filled polypropylene, which is obtained by blending an inorganic filler with crystalline polypropylene, has recently been used as a material for plastic industrial parts such as home appliances and automobiles. However, this inorganic filler-filled polypropylene has the drawbacks of low impact strength and high density of molded products formed from it. For this reason, conventionally known inorganic filler-filled polypropylene can be used in applications where impact resistance is not particularly required, but it cannot be used in applications where both rigidity and impact resistance are required. . Therefore, in order to improve the impact resistance of conventional inorganic filler-filled polypropylene, we have developed a composition in which inorganic filler-filled polypropylene is blended with a large amount of rubber such as an amorphous ethylene-propylene copolymer, or a fine inorganic filler is used as an inorganic filler. Many compositions have been proposed. but,
Compositions obtained by blending a large amount of rubber improve the impact resistance of the molded product, but the rigidity and heat deformation resistance decrease, and it is difficult to uniformly knead the polypropylene, inorganic filler, and rubber, resulting in poor appearance of the molded product. is bad and impractical. In addition, compositions obtained by blending fine inorganic fillers improve the Izod impact strength of molded products, but this composition can be molded into large molded products with a length of about 1 m to assemble home appliances, automobiles, etc. When we observed the presence or absence of breakage due to practical impact using aluminum molded products, we found that they often broke unexpectedly and were not suitable for practical use. This suggests that if the composition has high rigidity, the Izot impact strength of the test piece alone is insufficient as a criterion for determining the impact resistance when the composition is molded into a large molded product. It is something to do. The inventors have conducted various studies on methods for determining impact strength, which shows a good response to practical impacts when molded into large molded products.
Surface impact strength determined by the measurement method described below (a type of falling weight impact strength that indicates the energy required to break due to falling weight, sometimes abbreviated as HSI)
It has been found that when the Izot impact strength at 23°C is 10 Kg·cm/cm or more, almost no breakage occurs due to practical impact. Based on the above-mentioned opinion, the inventors determined that the rigidity of a molded product is determined by the flexural modulus, the heat deformation resistance is determined by the heat deformation temperature, and the impact resistance is determined by the Izot impact strength and the above-mentioned surface impact strength. Focusing on
The results of intensive research aimed at improving the above-mentioned drawbacks of conventionally known inorganic filler-containing polypropylene compositions and obtaining a polypropylene composition that has no practical problems as a material for large molded products used in home appliances, automobiles, etc. The above object can be achieved by blending talc with a specific particle size and an amorphous ethylene-propylene copolymer with a specific Mooney viscosity in a specific ratio into the specific crystalline ethylene-propylene block copolymer of the present invention. He discovered what could be achieved and completed this invention. That is, this invention has an ethylene content of 20% by weight or less and a melt flow rate (MFR) of 2 to 10%.
g/10 minutes, 5-15% by weight of para-xylene soluble content at room temperature, 25-45% ethylene content of the para-xylene soluble content at room temperature, intrinsic viscosity [η] (decalin,
135°C) 3-5 dl/g crystalline ethylene-propylene block copolymer (a), Mooney viscosity ML ₁₊₄ (100
℃) 15-100% amorphous ethylene-propylene copolymer (b) and talc (c) with an average particle size of 1-4.5 microns, the sum of each of the above components (a), (b) and (c)
This invention relates to a polypropylene composition for large-sized molded articles, in which (b) is blended in a ratio of 3 to 6% by weight and (c) is blended in a ratio of 18 to 30% by weight in 100% by weight. The composition of this invention has a density of 1.15 g/cm ³ or less,
Flexural modulus is 25000Kg/ ^cm2 or more, Izot impact strength (notched) at 23℃ is 10Kg/cm2 or more,
-10℃ surface impact strength is 350 as measured by the measurement method described below.
Kg・cm or more, heat deformation temperature is 120℃ or more, and even when molded into a large molded product with a length of 1m or more, it is glossy and no flow marks are observed. It has good moldability, and while retaining the inherent rigidity and heat deformation resistance of inorganic filler-filled polypropylene, the impact resistance, moldability, and appearance have been greatly improved, and it can be molded into large, lightweight molded products. can do. The crystalline ethylene-propylene block copolymer (a) used in the polypropylene composition for large molded articles of the present invention has an ethylene content of 20% by weight or less, and has a melt flow rate (MFR) of 20% by weight or less.
is 2 to 10 g/10 minutes, the room temperature para-xylene soluble content (consisting of an amorphous ethylene-propylene copolymer and a low molecular weight polymer) is 5 to 15% by weight, and the room temperature para- The ethylene content of the xylene soluble component is 25 to 45% by weight, and the room temperature par-
Intrinsic viscosity of xylene soluble component [η] (decalin, 135
°C) is 3 to 5 dl/g. In particular, the crystalline ethylene-propylene block copolymer suitably used in the polypropylene composition for large molded articles of the present invention has an ethylene content of 3 to 15% by weight.
with a melt flow rate (MFR) of 3~
10g/10 minutes, the room temperature para-xylene soluble content is 7 to 12% by weight, and the room temperature para-xylene soluble content is 30 to 40% by weight, and the room temperature para-xylene soluble content is 30 to 40% by weight. - The intrinsic viscosity [η] (decalin, 135°C) of the xylene soluble component is 3 to 5 dl/g. If the crystalline ethylene-propylene block copolymer used is outside the range specified above, it will not be possible to achieve the desired large molded product with excellent rigidity and heat deformation resistance, high impact strength, light weight, and good appearance. It is not possible to obtain polypropylene compositions that provide Although it is not clear why the polypropylene composition of this invention exhibits good physical properties when molded into a large molded article, it is clear that the specific crystalline ethylene-propylene block copolymer used in this invention and the amorphous ethylene- It is thought that some kind of strong interaction occurs between the propylene copolymer and talc. The crystalline ethylene-propylene block copolymer (a) is a crystalline ethylene-propylene block copolymer (a) or an amorphous ethylene-propylene copolymer.
(b) and talc (c) in a total of 100% by weight.
It is blended in an amount of 65 to 79% by weight, particularly preferably 70 to 77% by weight. The above content is less than 65% by weight or 79
If the amount exceeds % by weight, the rigidity and heat deformation resistance of the molded article tend to decrease, or the impact resistance of the molded article tends to decrease. Two or more types of crystalline ethylene-propylene block copolymers may be used as long as the total amount is within the above range. Amorphous ethylene-propylene copolymer (b) used in the polypropylene composition of this invention
has a Mooney viscosity ML ₁₊₄ (100°C) of 15 to 100 and preferably has an ethylene content of 50 to 90% by weight. Mooney viscosity ML ₁₊₄ (100℃) above
If it is less than 15, the rigidity and impact resistance of the molded article will decrease, and if it exceeds 100, it will be difficult to uniformly disperse the amorphous ethylene-propylene copolymer by kneading. The amorphous ethylene-propylene copolymer (b) is blended in an amount of 3 to 6% by weight in a total of 100% by weight of the components (a), (b) and (c). If the above blending amount is less than 3% by weight, the isot impact strength and surface impact strength (HSI) of the molded product will decrease, and if it exceeds 6% by weight, the flexural modulus of the molded product will decrease and the heat resistance will decrease. Deformability decreases. Two or more types of amorphous ethylene-propylene copolymers may be used as long as the total amount is within the above range. The talc used in the polypropylene composition of this invention has an average particle size of 1 to 4.5 microns;
Preferably it is between 1.5 and 3.5 microns. The average particle size here refers to the particle size at the 50% point on the particle size distribution integral curve. If the above average particle size is less than 1 μm, the surface impact strength of the molded product will be small, and if the above average particle size exceeds 4.5 μm, the flexural modulus, Izot impact strength, and surface impact strength of the molded product will decrease. becomes smaller. The talc (c) is present in an amount of 18 to 30% by weight, preferably 20 to 30% by weight, based on the total 100% by weight of each component (a), (b), and (c).
Contains 30% by weight. If the above compounding amount is less than 18% by weight, the flexural modulus of the molded product will be small and the heat distortion temperature will be low.
If the amount exceeds % by weight, the isot impact strength and surface impact strength of the molded article will decrease, the density will increase, and the moldability of the composition will decrease. Talc may be used untreated, but in order to improve its dispersibility, various organic titanate coupling agents, silane coupling agents, saturated or unsaturated fatty acids, carboxylic acids with vinyl unsaturated bonds, fatty acid metals may be used. Particle surfaces coated with salt, fatty acid ester, fatty acid amide, etc. may also be used. Two or more types of talc may be used as long as the total amount is within the above range. The polypropylene composition of this invention can be used in a Banbury mixer, twin screw extruder, FCM, kneader,
It can be produced using a kneading machine such as a stage twin-screw extruder or a KCK extruder. Usually, the composition is kneaded in the above-mentioned kneading machine to form a pellet-like composition, which is then subjected to processing. The pellet-like composition was prepared by kneading talc in advance as a high-concentration masterbatch (the above-mentioned crystalline ethylene-propylene block copolymer was used as the base polymer), an additional crystalline ethylene-propylene block copolymer and It may be produced by diluting it with a regular ethylene-propylene copolymer, or it may be produced by directly kneading each component. Other resins such as high-density polyethylene, other rubbers, or other inorganic fillers such as calcium carbonate, barium sulfate,
Appropriate amounts of mica, clay, titanium oxide, diatomaceous earth, bolast, etc. can be blended into the polypropylene composition of the present invention. In addition, in order to further improve the various performances of molded articles formed from the polypropylene composition of the present invention, there is also a method of adding the polypropylene composition at the time of mixing, after mixing each component, or to the polymer component in advance. 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl -α-dimethylamino-para-cresol, 6-(4-hydroxy-3,5-di-tert-butylanilino)-2,
4-bisoctyl-thio-1,3,5-triazine, n-octadecyl-3-(4'-hydroxy-
3',5'-di-tert-butylphenyl) propionate, 2,6-di-tert-butyl-4-methylphenol (BHT), tris-(2-methyl-4-hydroxy-5-tert-butylphenyl) butane, tetrakis -[Methylene 3-(3',5'-di-tert-butyl-
4'-Hydroxyphenyl)propionate] methane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, dilaurylthiodipropionate, etc. Antioxidant; 2-hydroxy-4-n-
Octoxybenzophenone, 2-hydroxy-4
-octadecyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, nickel-bis-(orthoethyl-3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate, 2
-hydroxy-4-n-octoxybenzophenone, 2-(2'-hydroxy-3'-tert-butyl-5'-
methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butyl-phenyl)-5-chlorobenzotriazole,
UV absorbers such as bis-(2,6-dimethyl-4-piperidyl) sebacate; flame retardants such as antimony trioxide, tricresyl phosphate, halogenated alkyl triazine, decabrom diphenyl ether, and chlorinated polyethylene; carbon Pigments such as black and titanium oxide; paintability improvers such as magnesium benzoate; plasticizers such as process oil; lubricants such as fatty acid metal salts; and antistatic agents such as polyoxyethylene alkyl ether. You can also do that. Molding the polypropylene composition of the invention by a method known per se, for example injection molding,
It is possible to obtain a large, highly rigid molded product with excellent rigidity and heat deformation resistance, high impact strength, light weight, and good appearance and durability. Examples and comparative examples are shown below. In the following description, "parts" and "%" mean "parts by weight" and "% by weight", respectively, and melt flow rate (MFR)
According to ASTM D1238 (230℃, 2.16Kg), the density is
ASTM D1505, flexural modulus is ASTM D790
, Izot impact strength to ASTM D256, heat distortion temperature to ASTM D648, Mooney viscosity ML ₁₊₄
(100°C) was measured according to JIS K6300. Also,
Surface impact strength (HSI) is the energy required to break when a steel falling weight with a tip diameter of 2.5 cm collides with a 1.6 mm thick molded product at a speed of 2.5 m/sec, and is the stress that indicates the relationship between stress and strain. -Displayed by the area surrounded by the strain curve and each axis. The para-xylene soluble portion of crystalline polypropylene at room temperature (approximately 20°C) is obtained by adding 5 g of polymer to 500 ml of para-xylene together with approximately 1% antioxidant, completely dissolving it under heating, and then leaving it at room temperature overnight. The precipitated insoluble matter was removed by centrifugation, the soluble matter solution was poured into acetone, and the precipitated insoluble matter was dried under reduced pressure.
The ethylene content of the soluble portion was determined by the Gardner method, and the intrinsic viscosity [η) was determined at 135°C using decalin as a solvent. Example 1 Ethylene content 7%, melt flow rate (MFR) 3 g/10 min, normal temperature para-xylene soluble content
Crystalline ethylene-propylene block copolymer (hereinafter referred to as
EP copolymer A) 71 parts and Mooney viscosity
ML ₁₊₄ (100℃) 65, intrinsic viscosity [η] 2.3dl/g
(decalin, 135°C, the same applies hereinafter), 4 parts of amorphous ethylene-propylene copolymer (hereinafter referred to as EPR-A) with an ethylene content of approximately 70%, 25 parts of talc with an average particle size of 2.8μ, and tetrakis- [Methylene 3-
(3',5'-Ditert-butyl-4'-hydroxyphenyl)propionate] 0.1 part of methane and 0.1 part of BH were mixed in a tumbler for 15 minutes, then heated at 220°C in a twin-screw extruder. The mixture was kneaded, extruded, and pelletized. Melt flow rate (MFR) of the obtained pellet-like polypropylene composition, and density, flexural modulus, isot impact strength, surface impact strength, and heat distortion temperature of test pieces obtained from this composition by injection molding. are shown in Table 1. In addition, large molded products (length:
It is formed into a box shape of 135 cm and 30 cm deep with a wall thickness of 3 mm.
The first step was to judge the moldability and observe the appearance.
Shown in the table. Comparative Example 1 As a crystalline ethylene-propylene block copolymer, ethylene content was 3%, MFR was 3 g/10 min,
Room temperature para-xylene soluble content 4.2%, room temperature para-
Ethylene content of xylene soluble portion: 35.0%, [η]
The same procedure as in Example 1 was carried out except that a 3.8 dl/g crystalline ethylene-propylene block copolymer (hereinafter referred to as EP copolymer a) was used. The results are summarized in Table 1.

[Table] Examples 2 to 3, Comparative Examples 2 to 3 Same as Example 1 except that polypropylene of the type shown in Table 2 was used instead of EP copolymer A as the crystalline ethylene-propylene block copolymer. carried out. The results are summarized in Table 3.

【table】

[Table] Examples 4 to 5, Comparative Example 4 The same procedure as in Example 2 was carried out except that a rubber of the type shown in Table 4 was used instead of EPR-A as the amorphous leethylene-propylene copolymer. The results are summarized in Table 5.

【table】

[Table] Examples 6 to 7, Comparative Examples 5 to 6 The same procedure as in Example 1 was carried out except that the types of talc shown in Table 6 were used as the talc. The results are summarized in Table 6.

[Table] Examples 8 to 10, Comparative Examples 7 to 10 The same procedure as in Example 1 was carried out except that the blending ratio of each component was changed. The results are summarized in Table 7.

【table】

【table】

Claims (1)

[Scope of Claims] 1. Ethylene content of 20% by weight or less, melt flow rate (MFR) of 2 to 10 g/10 minutes, 5 to 15% by weight of para-xylene soluble content at room temperature, and a content soluble in para-xylene at room temperature. , a crystalline ethylene-propylene block copolymer (a) having an ethylene content of 25 to 45% by weight and an intrinsic viscosity [η] (decalin, 135°C) of 3 to 5 dl/g;
Consisting of an amorphous ethylene-propylene copolymer (b) with a Mooney viscosity of ML ₁₊₄ (100°C) 15 to 100, and talc (c) with an average particle size of 1 to 4.5 microns, each of the above components (a), ( 3 to 3 (b) in 100% by weight of b) and (c)
A polypropylene composition for large-sized molded articles, comprising 4.5% by weight of (c) and 18-30% by weight of (c).