JPH03197542A - Resin composition for blow molding - Google Patents

Abstract

PURPOSE:To prepare the title compsn. excellent in the blow moldability, coatability, and planishability of the coated surface by compounding a polypropylene resin, a high-density polyethylene resin, a rubberlike polymer, and an inorg. powder, the foregoing two resins having each a specified melt index. CONSTITUTION:The title compsn. is prepd. by compounding 30-70wt.% polypropylene resin having a melt index of 0.8g/10min or lower and pref. being an ethylene-propylene block copolymer contg. 20wt.% or lower ethylene units; 10-30wt.% high-density polyethylene resin having a melt index of 0.05g/10min or lower and an intrinsic viscosity of 3.5dl/g or higher; 10-30wt.% rubberlike polymer pref. being an ethylene-propylene copolymer rubber (EPM) or an ethylene-propylene-diene terpolymer rubber (EPDM); and 5-30wt.% inorg. powder having a mean particle diameter of 10mu or lower.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a novel resin composition for blow molding, more specifically, it is capable of large-scale blow molding, has excellent paintability and mirror finish after painting, The present invention also relates to a resin composition for blow molding, which can provide molded articles with good mechanical properties and is suitable as a material for automobile exterior parts such as bumpers, spoilers, and side moldings.

[Prior art] Polyolefin resins generally have excellent processability, chemical resistance, weather resistance, electrical properties, etc. Among them, polypropylene and polyethylene have good processability and when molded into a molded product, the surface of the resin is excellent. Because it has a smooth, glossy and beautiful appearance, it is widely used in various fields such as home appliances, OA equipment, automobile parts, various injection molded products, blow molded products, vacuum and pressure molded products, films, and sheets. It is used.

Around 7 years ago, automobile exterior parts such as bumpers, spoilers, and side moldings were traditionally made by injection molding or extrusion molding of thermoplastic resin, or aged molding of thermosetting resin, but recently they have been made in small quantities and in large quantities. As the need for different types increases, the development of large blow molded parts for automobile exteriors is desired. Blow molding materials used for such automobile exterior parts are required to have good blow moldability such as drawdown resistance, as well as excellent paintability and mirror finish after painting.

On the other hand, in order to improve the mechanical properties, heat resistance, paintability, etc. of polyolefin resins, inorganic fillers have been widely incorporated into polyolefin resins. Attempts have also been made to incorporate propylene copolymer rubber.

However, conventional polyolefin resin materials have excellent blow moldability such as drawdown resistance, which is suitable as a material for large blow molded parts for automobile exteriors such as bumpers, spoilers, and side moldings, as well as paintability. At present, it has not necessarily been possible to find a material that has excellent specularity and good mechanical properties after painting.

[Problems to be Solved by the Invention] Under these circumstances, the present invention has excellent blow moldability such as drawdown resistance, and is capable of large-scale blow molding.
The present invention has been made with the aim of providing a polyolefin resin material for blow molding that has excellent paintability and mirror finish after painting, and also has good mechanical properties.

[Means for Solving the Problems] The present inventors have conducted intensive research to develop a polyolefin resin material for blow molding having the above-mentioned preferable properties. It was discovered that this objective could be achieved by a resin composition containing a high-density polyethylene having a melt index and an intrinsic viscosity, a rubber-like polymer, and an inorganic powder having a specific average particle size in predetermined proportions. The present invention was completed based on this.

That is, the present invention provides (A) a melt index of 0.8
30 to 70% by weight of polypropylene resin with a melt index of 34 g/10 minutes or less, (B) 10 to 30% by weight of high-density polyethylene with a melt index of 3.4 g/10 minutes or less and an intrinsic viscosity of 3.5 dl/y or more, (C) rubber 10 to 30% by weight of polymer and (D) average particle size of 10 μm
The present invention provides a blow molding resin composition characterized by containing 5 to 30% by weight of the following inorganic powder.

The present invention will be explained in detail below.

In the composition of the present invention, the polypropylene resin used as component (A) is not particularly limited, and may be a homopolymer of propylene or a copolymer of propylene and other σ-olefin. or a mixture thereof. Other olefins used in this copolymer include those having 2 to 8 carbon atoms, such as ethylene, 1-butene, 1-pentene, and hexene-1.
Preferred examples include 1, heptene-1, and octene-1. As the copolymer, a block copolymer or a random copolymer containing the above-mentioned other α-shaped fin units, usually 40% by weight or less, preferably 30% by weight or less, can be used, but especially 20% by weight or less, and preferably 30% by weight or less, can be used. Propylene-ethylene block copolymers containing up to % by weight of ethylene units are preferred.

The polypropylene resin as the component (A) in the composition of the present invention needs to have a melt index of 0.8 g/10 minutes or less, preferably 0.6 g/10 minutes or less. This melt index is 0.8. If the time exceeds y/10 minutes, blow molding of large molded products such as bumpers becomes difficult, and the object of the present invention cannot be fully achieved. Also, 2
When using a mixture of more than one type of polypropylene resin,
The respective melt indexes of polypropylene with the highest melt index and polypropylene with the lowest melt index are M I PF (large) and M
If I pr (small), then MIPP (large) / M
It is desirable that the I PF (small) ratio is 3 or less.

When this ratio exceeds 3, there is a tendency for the blower characteristics to deteriorate.

The polypropylene resin as component (A) must be contained in the composition in an amount of 30 to 70% by weight, preferably 30 to 60% by weight. If the content is less than 30% by weight, high-temperature rigidity may be insufficient and paintability may be poor; if it exceeds 70% by weight, drawdown resistance may decrease and blow molding may become difficult. It will be done.

The high-density polyethylene as component (B) in the composition of the present invention usually has a density of 0.938 to 0.
．． A material in the range of 970 g/C113 is used. One type of high-density polyethylene may be used or a combination of two or more types may be used, but the melt index thereof is o, os, 710 minutes or less, preferably 0.0
39/10 minutes or less, and the intrinsic viscosity [y+] is 3.5
It is necessary that it is dQ/g or more. If this melt index exceeds 0.059/10 minutes or if the intrinsic viscosity [η] is less than 3.5 dl19, it will be difficult to blow mold large molded products such as bumpers, and the purpose of the present invention may not be fully achieved. do not have.

This high-density polyethylene as component (B) contains 1
It is necessary to contain it in a proportion of 0 to 30% by weight, preferably io to 20% by weight.

If the content is less than 10% by weight, drawdown resistance and blow-up properties may deteriorate, making blow molding difficult. If it exceeds 30% by weight, paintability and mirror finish of the coating film tend to deteriorate. Be looked at.

In the composition of the present invention, there are no particular limitations on the rubbery polymer used as component (C), such as ethylene-α-olefin copolymer rubber, ethylene-α-olefin-nonconjugated diene copolymer rubber, etc. Preferably used. Examples of the α-olefin include those having 3 to 12 carbon atoms, with propylene being particularly preferred. Also,
Examples of non-conjugated diene compounds include 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, dicyclopentadiene, methylenenorbornene, ethylidenenorbornene, cyclooctadiene, methyltetrahydroindene, and the like. But among these, 1
, 4-hexadiene, ethylidene norbornene and dicyclopentadiene are preferred.

Examples of the rubbery polymer of component (C) include ethylene-propylene binary 11-+'' rubber (EPM) and ethylene-propylene-diene ternary copolymer rubber (EPDM).
) is preferred. One type of the rubbery polymer may be used, or two or more types may be used in combination, and the content thereof in the composition is selected within the range of 10 to 30% by weight. If the content is less than 10% by weight, the paintability and specularity of the coating film will be insufficient, and if it exceeds 30% by weight, the rigidity will tend to decrease.

Further, in the composition of the present invention, it is desirable that the total content of the high-density polyethylene as the component (B), the component (C), and the rubbery polymer is 50% by weight or less; %, there is a tendency for stiffness to decrease.

As the inorganic powder of component (D) in the composition of the present invention,
For example, silica, diatomaceous earth, barium ferrite, beryllium oxide, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, calcium carbonate, magnesium carbonate, dolomite, dawsonite, calcium sulfate, barium sulfate, ammonium sulfate, calcium sulfite, talc, clay, Calcium silicate, montmorillonite, bentonite, carbon black, graphite,
Molybdenum sulfide, zinc borate, notrium metaborate,
Calcium borate, sodium borate, etc., or zinc, copper, iron, lead, aluminum, dimethyl, chromium,
Metal elements such as titanium, manganese, soot, platinum, tungsten, gold, magnesium, cobalt, strontium and oxides of these metals, stainless steel, solder, alloys such as brass, silicon carbide, silicon nitride, zirconia,
Examples include powders of metallic ceramics such as aluminum nitride and titanium carbide, and among these, talc is particularly suitable.

This inorganic powder of component (D) may be used alone or in combination of two or more, but the average particle size is 1
It is necessary that the thickness is 0 μm or less, preferably 5 μm or less. When the average particle size exceeds 10 μm, there is a tendency for the blow-up characteristics and paintability to deteriorate.

In the present invention, the inorganic powder can be used after being surface-treated with a known surface-treating agent, if desired. Examples of the surface treatment agent include saturated higher fatty acids or derivatives thereof such as stearic acid and palmitic acid, unsaturated higher fatty acids such as oleic acid or derivatives thereof, silane coupling agents, titanate coupling agents, silicone oils, Examples include alcohol, and one type of these may be used, or two or more types may be used in combination.

There are no particular limitations on the method of surface treating the inorganic powder using these surface treating agents; for example, the surface treating agent may be sprayed onto the inorganic powder in a Henschel mixer, and the treatment may be carried out by mixing and stirring. , may be treated simultaneously at the inorganic powder manufacturing stage.

The content of the inorganic powder as component (D) in the composition of the present invention is selected in the range of 5 to 30% by weight, preferably 10 to 25% by weight. If the content is less than 5% by weight, the paintability and specularity of the coating film will be insufficient, and if it exceeds 30% by weight, the blow-up properties and drawdown resistance will decrease, making blow molding difficult. There is a tendency for the strength of the parting line to decrease.

The composition of the present invention may optionally contain other thermoplastic resins, fibrous inorganic fillers, organic fillers, antioxidants, light stabilizers, heat stabilizers, and lubricants to the extent that the purpose of the present invention is not impaired. , a catalyst neutralizer (halogen scavenger), an antistatic agent, a flame retardant, a coloring agent, a mold release agent, etc. can be added.

Examples of the thermoplastic resin having the above properties include polyolefin resins such as medium and low density polyethylene, modified polypropylene, and polybutene-1, polyvinyl chloride resins, polyamide resins, polyimide resins, polysulfone resins,
Polyacetal resin, polycarbonate resin, polyaromatic ether or thioether resin, polyaromatic ester resin, polysulfone resin, styrene resin,
Examples include acrylate resins.

Examples of fibrous inorganic fillers include glass fiber, carbon fiber, poron fiber, aluminum fiber, stainless steel fiber,
Examples include metal fibers such as copper fibers, brass fibers, nickel fibers, silicon carbide fibers, single crystal potassium titanate, other single metal fibers, alloy fibers, and metal whiskers corresponding to these fibers. In addition, as an organic filler,
Examples include rice husk fiber, wood flour, cotton, jute, paper strips, cellophane strips, aromatic polyamide fibers, cellulose fibers, nylon fibers, polyester fibers, polypropylene fibers, and the like. Preferable examples of antioxidants include phenol-based and phosphorus-based antioxidants, and combinations of these are particularly preferred. Examples of phenolic antioxidants include 2,6-di-t-butyl-
4-methylphenol, tris(3,5-di[-butyl-4-hydroxybenzyl)isocyanurate (manufactured by Ciba Geigy, Irganox 3114), 2.2″-methylenebis(4-ethyl-6-t-butylphenol),
n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate (manufactured by Ciba Geigy, Irganox 1076), 4.4''-thiobis(3-methyl-6-t-butylphenol) ), tetrakis[methylene-3-(3′,5″-di-t-butyl-4′-hydroxyphenyl)propionate comethane (manufactured by Ciba Geigy, Irganoxlolo), 4
．． 4'-butylidenebis(3-methyl-6-t-butylphenol), 2.2'-methylenebis(4-methyl-
6-t-butylphenol), N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxyhydrocinnamide) (manufactured by Ciba Geigy, Irgano
x109B), triethylene glycol-bis[3-(
3'=t-butyl-5'-methyl-4-hydroxyphenyl)propionate], a mixture of calcium bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate) and PR wax (weight ratio 1 :1) (manufactured by Ciba Geigy, Irganox1425WL). Examples of phosphorus antioxidants include distearyl pentaerythritol diphosphite and tetrakis (
2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphite (manufactured by Sandoz, 5anaostab
P-EPQ), trisnonylphenyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, and the like.

Examples of light stabilizers used include salicylates, benzophenones, triazoles, oxalate trilides, and hindered amines. Examples of lubricants include stearamide, balmitic acid amide, oleic acid amide, and erucic acid. Examples of catalyst neutralizers include calcium stearate, zinc stearate,
Examples include higher fatty acid metal salts such as magnesium stearate and hydrotalcite.

The resin composition of the present invention comprises a required amount of the component (A), (B
) components, (C) components, (D) components, and various additive components used as necessary, such as FCM, twin screw continuous extruder, kneader, Henschel mixer, Pan Bali mixer,
It can be prepared by melt-kneading using a roll or the like.

At this time, it is desirable to adopt conditions such that the melt index of the kneaded product does not become too high, that is, conditions that suppress deterioration due to shear heat generation during kneading.

The resin composition for blow molding of the present invention thus obtained is processed using a method conventionally used in blow molding polypropylene or high-density polyethylene, for example, at a molding temperature of 190 to 260°C, a mold temperature of 20 to 80°C. By blow molding under the conditions of .degree. C., it is possible to obtain a large molded product with excellent paintability and mirror finish after painting.

[Example] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

In addition, each characteristic was calculated|required as follows.

(1) Melt index (MI') JIS K
-7210. The melt index of the polypropylene resin was measured at 230°C under a load of 121609, and the melt index of high-density polyethylene was measured at 190°C and a load of 21609.

(2) Intrinsic viscosity [V] Measured according to JISZ-8803. Note that decalin was used as the solvent, and the test temperature was 135°C.

(3) Bumper formability Using a die with a diameter of 310 mm, the length of the parison is 2.50 mm.
A bumper weighing 9.04 kg was molded under conditions of 0 mm and a weight of 18.57+g, and moldability was evaluated according to the following criteria.

○: Can be molded x (I) There is a problem with the nitro-down, so it cannot be molded. Painted,
After cutting the flat surface of this painted bumper, the beer strength was determined by the following method and the urethane paintability was evaluated.

(5) Specularity of the coating film When the cut-out piece of the urethane-coated bumper obtained in (4) above is tilted at a 45° angle to the fluorescent lamp, the outline of the fluorescent lamp is clearly recognized as ○. The specularity of the coating film was evaluated, with those that could not be evaluated as x.

In addition, the following polypropylene resin was used.

(1) Block PP (a): MI = 0.50, ethylene content - 1.8 mol% (2) Block PP (b): MI = 0.15, ethylene content - 10 mol% (3) Block PP ( c): MI=6.0, ethylene content -6 mol% Examples 1 to 7,
Comparative Examples 1 to 7 Each component of the type and amount shown in Table 1 was supplied to a twin screw extruder [Kobe Steel, Ltd., Department 2FCM] and heated at 220°C to 250°C.
A resin composition was prepared by melt-kneading, and its performance was evaluated. The results are shown in Table 1.

(The following is a blank space) 19 [Effects of the Invention] According to the present invention, a molded product for blow molding that is capable of large-scale blow molding, has excellent paintability and mirror finish after painting, and can give molded products with good mechanical properties. A polyolefin resin composition can be easily obtained.

Since the blow molding resin composition of the present invention has the above-mentioned excellent characteristics, it can be used, for example, in bumpers, spoilers, etc.
It is suitably used as a blow molding material for automobile exterior parts such as side moldings.

Claims (1)

[Claims] 1 (A) 30 to 70% by weight of a polypropylene resin with a melt index of 0.8 g/10 minutes or less, (B) a melt index of 0.05 g/10 minutes or less and an intrinsic viscosity of 3.5
10 to 30% by weight of high-density polyethylene of dl/g or more,
A resin composition for blow molding, comprising (C) 10 to 30% by weight of a rubbery polymer and (D) 5 to 30% by weight of an inorganic powder having an average particle size of 10 μm or less. 2. The composition according to claim 1, wherein the inorganic powder is talc. 3. Total content of component (B) and component (C) is 50% by weight
The composition according to claim 1 or 2, which is as follows.