JP2000230087A - Propylene resin composition for blow molding and molding made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a propylene resin composition excellent in draw down resistance and suitable for lowly glossy large blowing moldings by compounding a polypropylene resin and a polyethylene resin each having a specified melt flow rate with an inorganic filler, a rubbery polymer, and an organic peroxide in a specified ratio and melt-kneading the resultant mixture. SOLUTION: This composition is prepared by melt-kneading a mixture comprising 40-99 wt.% polypropylene resin having a melt flow rate of 0.1-1 g/10 min and desirably having an ethylene content of 1-30 wt.%, 1-40 wt.% polyethylene being a high-density polyethylene having a melt flow rate of 0.01-0.5 g/10 min and desirably having a density of 0.940 g/cm3, 0-30 wt.% inorganic filler (e.g. talc), 0-30 wt.% rubbery polymer (e.g. ethylene/propylene rubber), and 0.001-0.2 pt.wt., per 100 pts.wt., total of the four former components, organic peroxide [e.g. 1,3-bis(t-butylperoxyisopropyl)benzene).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a propylene-based resin composition for blow molding and an automobile part using the same. More specifically, the present invention relates to a propylene-based resin composition suitable for large-size blow molding having a parison weight of 1 kg or more, and to an automotive interior / exterior part blow-molded using the same.

[0002]

2. Description of the Related Art Thermoplastic resins are lightweight and have good moldability, and are used for interior and exterior parts of automobiles, electric appliance parts for home electric appliances, etc., and the molded articles usually have high gloss.
However, in recent years, low-gloss molded articles have been demanded for the purpose of giving quality and a sense of calm or for the purpose of protecting users from visual dazzle. Conventionally, blow-molded products are inferior to injection-molded products due to the lower resin pressure on the mold during shaping, resulting in poor mold transferability, poor surface appearance, and are not suitable for appearance-oriented products. . However, since the molding material used for blow molding is required to have drawdown resistance of the parison, it is generally made to have a high molecular weight, and there is an advantage that a tough molded product having excellent rigidity and impact resistance can be obtained. . In recent years, in the field of large blow molded products, development of large components that are structural components and appearance components while utilizing their toughness has been progressing. By the way, some improvement proposals for reducing glossiness which have been made so far are as follows. (1) There is a method of applying a matting agent to the surface of a molded product,
The coating process is costly, and the surface of the resin may be deteriorated by the solvent. (2) Method of blending an inorganic filler (Japanese Patent Publication No. 49-445)
No. 82), but a small amount has no effect, and a large amount reduces impact resistance. (3) A method of adding a rubber-modified thermoplastic resin (JP-A-5
JP-A-6-133353, JP-A-59-89346, JP-A-60-18536, etc.), but the degree of matting varies depending on molding conditions. Therefore, these proposals are still not enough.

[0003]

DISCLOSURE OF THE INVENTION The present invention relates to a resin composition for blow molding having good drawdown resistance and low gloss, particularly a resin composition suitable for large blow molding and an automobile using the same. The purpose is to provide exterior parts.

[0004]

Means for Solving the Problems The present inventors have studied the dominant factors affecting the gloss of the surface of a blow-molded product, based on a molding material having good drawdown resistance suitable for large-size blow molding. The basic material is composed of two kinds of high molecular weight polyolefins, that is, polypropylene resin and polyethylene resin, and when this is decomposed with organic peroxide, it is found that the gloss of the surface state of the molded product is reduced, and is shown below. The present invention has been completed.

That is, the present invention provides the following. (1) (A) Melt flow rate (MFR) is 0.1 to
40 to 99% by weight of a polypropylene resin which is 1 g / 10 min, (B) a melt flow rate (MFR) of 0.01 to
0.5 g / 10 min of polyethylene resin 1 to 40% by weight, (C) 0 to 30% by weight of inorganic filler, (D) 0 to 30% by weight of rubbery polymer and (E) organic peroxide A propylene-based resin composition for blow molding obtained by blending 0.001 to 0.2 parts by weight with respect to 100 parts by weight of the total of the components (A), (B), (C) and (D) and melt-kneading the mixture. (2) The propylene resin composition for blow molding according to the above (1), wherein the polypropylene resin as the component (A) has an ethylene content of 1 to 30% by weight. (3) The density of the polyethylene resin (B) is 0.940.
The propylene resin composition for blow molding according to the above (1) or (2), which is a high-density polyethylene having a g / cm ³ or more. (4) The propylene-based resin composition for blow molding according to any one of (1) to (3), wherein the parison weight in blow molding is 1 kg or more. (5) Interior / exterior parts for automobiles blow-molded using the propylene resin composition for blow molding according to any one of (1) to (4).

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Polypropylene resin] The polypropylene resin used as the component (A) in the resin composition of the present invention is not particularly limited, and may be a propylene homopolymer. It may be a copolymer. Further, a mixture thereof may be used. Among them, a copolymer of propylene and an α-olefin can be particularly preferably used. The α-olefin used in the copolymer is one having 2 to 10 carbon atoms, such as ethylene, butene-1, pentene-1, hexene-
1, heptene-1, octene-1 and the like. As the copolymer, a block copolymer or a random copolymer containing usually 40% by weight or less, preferably 30% by weight or less of an α-olefin unit can be used, and particularly 3 to 20% by weight. Propylene-ethylene block copolymers containing ethylene units can be suitably used.

[0007] The polypropylene resin of the component (A)
230 ° C, load 2.1 according to JIS K-6758
The melt flow rate (MFR) measured at 6 kgf is 0.1 to 1 g / 10 min, preferably 0.2 to 0.7 g /
10 minutes. If the MFR is less than 0.1 g / 10 minutes, the fluidity is reduced. If the MFR is more than 1 g / 10 minutes, the drawdown resistance becomes insufficient and blow molding becomes difficult.

[Polyethylene resin] The polyethylene resin used as the component (B) in the resin composition of the present invention includes:
There is no particular limitation, and it may be HDPE (high density polyethylene), LDPE (low density polyethylene) or LPE.
LDPE (linear low density polyethylene) may be used. Further, a mixture thereof may be used. Especially H
DPE can be suitably used. HDPE having a density of 0.94 g / cm ³ or more is used as the component (B). If the density is less than 0.94 g / cm ³ , the rigidity will decrease.

[0009] The polyethylene resin of the component (B)
190 ° C., load 2.16 according to IS K-6758
The melt flow rate (MFR) measured in kgf is 0.
01 to 0.5 g / 10 min, preferably 0.015 to 0.1 g.
3 g / 10 min, more preferably 0.02 to 0.1 g / 1
0 minutes. If the MFR is less than 0.01 g / 10 minutes, the moldability is reduced, and if it is more than 0.5 g / 10 minutes, the drawdown resistance becomes insufficient, and blow molding becomes difficult.

[Inorganic filler] In the resin composition of the present invention, an inorganic filler can be blended if necessary.
Examples of the inorganic filler include silica, diatomaceous earth, barium ferrite, beryllium oxide, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, calcium carbonate, magnesium carbonate, magnesium sulfate,
Dolomite, dawsonite, calcium sulfate, barium sulfate, ammonium sulfate, calcium sulfite, talc,
Clay, calcium silicate, montmorillonite, bentonite, carbon black, graphite, molybdenum sulfide, zinc borate, barium metaborate, calcium borate, sodium borate, etc., or zinc, copper, iron,
Metals such as lead, aluminum, nickel, chromium, titanium, manganese, tin, platinum, tungsten, gold, magnesium, cobalt, strontium and their metal oxides, alloys such as stainless steel, solder, brass, silicon carbide, silicon nitride , Zirconia, aluminum nitride, metal carbides such as titanium carbide and the like, and powders and fibers. Of these, talc is particularly preferable. One of these inorganic fillers may be used, or two or more thereof may be used in combination.

The average particle size when the inorganic filler is a powder,
Alternatively, in the case of a fiber, the average fiber thickness is usually 10 μm or less, preferably 5 μm or less. If it exceeds 10 μm, color unevenness may occur and the appearance may deteriorate. The inorganic filler can be used after being surface-treated with a known surface treatment agent, if necessary. As this surface treatment agent,
Examples thereof include saturated higher fatty acids such as stearic acid and palmitic acid or derivatives thereof, unsaturated higher fatty acids such as oleic acid and derivatives thereof, silane coupling agents, titanate coupling agents, silicone oils, higher alcohols, and the like. There is no particular limitation on the method of surface treatment.For example, in a Henschel mixer, a surface treatment agent may be sprayed on the inorganic powder, and the mixture may be treated by mixing and stirring, or may be simultaneously treated in the step of producing the inorganic powder. Is also good.

[Rubber-like polymer] In the resin composition of the present invention, a rubber-like polymer can be blended if necessary. Examples of the rubbery polymer used in the present invention include polymers of conjugated diene compounds such as polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, and polyisoprene, and ethylene-propylene random copolymer (ethylene Propylene rubber), ethylene-α-olefin (having 4 to 10 carbon atoms) random copolymer, and olefin copolymer rubber such as ethylene-α-olefin-non-conjugated diene terpolymer. The α-olefin used here includes propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1 and the like. Among them, propylene and octene-1 are preferred. Similarly, non-conjugated dienes include 1,4-hexadiene and 1,6-hexadiene.
Chain non-conjugated dienes such as octadiene, cyclic non-conjugated dienes such as 1,4-cyclohexadiene, dicyclopentadiene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, and 2,3-diisopropylidene-5-norbornene And the like. One of them
4-hexadiene, dicyclopentadiene and 5-ethylidene-2-norbornene are preferred.

[0013] The olefin copolymer rubber is
Usually, those having an ethylene content of 40 to 90% by weight, an α-olefin copolymer of 10 to 60% by weight, and a non-conjugated diene content of 0 to 12% by weight can be used. Among the above rubber-like polymers, particularly, an ethylene-propylene random copolymer (ethylene-propylene rubber) and a binary copolymer rubber obtained by random copolymerizing ethylene and 1-octene can be suitably used.

[Organic peroxide] As the organic peroxide used in the present invention, for example, benzoyl peroxide, t-
Butyl perbenzoate, t-butyl peracetate,
t-butyl peroxyisopropyl carbonate, 2,
5-di-methyl-2,5-di- (t-benzoylperoxy) hexane, 2,5-di-methyl-2,5-di-
(T-benzoylperoxy) hexyne-3, t-butyl-di-peradipate, t-butylperoxy-3,
5,5-trimethylhexanoate, methyl-ethylketone peroxide, cyclohexanone peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,5-di-methyl-2,5-di- (t- Butylperoxy) hexane, 2,5-di-methyl-2,5
-Di- (t-butylperoxy) hexyne-3,1,3
-Bis- (t-butylperoxyisopropyl) benzene, t-butylcumyl peroxide, 1,1-bis-
(T-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis- (t-butylperoxy) cyclohexane, 2,2-bis- (t-butylperoxy) butane, p-menthane Hydroperoxide, di-isopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, p-cymene hydroperoxide, 1,1,3,3-tetra-methylbutyl hydroperoxide and 2,5 -Di-methyl-2,6-di- (hydroperoxy) hexane. In the present invention, the organic peroxide may be appropriately selected depending on the conditions for melting and kneading the resin composition. Melt kneading is usually 16
Perform at a temperature of 0 ° C. or higher.

[Blending] The resin composition of the present invention has (A) a melt flow rate (MFR) of 0.1 to 1 g / 10 minutes,
(B) a melt flow rate (MFR) of 0.01 to 40% by weight, preferably 50 to 80% by weight, preferably 0.2 to 0.7 g / 10 min.
0.5 g / 10 min, preferably 0.015 to 0.3 g /
10 minutes, more preferably 0.02 to 0.1 g / 10 minutes, 1 to 40% by weight of polyethylene resin, preferably 3 to
30% by weight, (C) 0-30% by weight of inorganic filler, preferably 5-25% by weight, (D) 0-30% by weight of rubbery polymer, preferably 3-25% by weight, and (E) organic The peroxide is used in an amount of 0.001 to 0.2 part by weight, preferably 0.003 to 0.1 part by weight, based on 100 parts by weight of the total of the components (A), (B), (C) and (D). And a propylene-based resin composition for blow molding which has been subjected to a melt-kneading treatment.

The polypropylene resin of the component (A) is
If it is less than 40% by weight, it may lead to a decrease in mechanical strength properties and moldability, and if it is more than 99% by weight, it is difficult to reduce gloss. If the content of the polyethylene resin (B) is less than 1% by weight, the drawdown resistance is insufficient, and if it is more than 40% by weight, the appearance is poor. Further, the inorganic filler of the above-mentioned component (C) may be added as necessary, but if it exceeds 30% by weight, the weld becomes conspicuous and the pinch-off strength decreases. The rubbery polymer as the component (D) may be added as required. However, if it exceeds 30% by weight, the appearance becomes poor, such as conspicuous welds and flow marks, and the decrease in gloss becomes insufficient.
If the amount of the organic peroxide (E) is less than 0.001 part by weight, the gloss is not sufficiently reduced, and if it exceeds 0.2 part by weight, the gloss is reduced. And blow molding becomes difficult.

In the propylene resin composition of the present invention, if necessary, known additives such as thermoplastic resins such as polypropylene and polyethylene, pigments, weathering agents, antioxidants, antistatic agents, flame retardants, and dispersants. Can be blended. The method for preparing the propylene-based resin composition of the present invention is not particularly limited, and for example, the component (A),
The component (B), the component (C), the component (D), the component (E) and other optional components used as necessary are mixed with a single screw extruder,
160-300 ° C., preferably 220-260, using a twin-screw extruder, Banbury mixer, kneader, roll or the like.
A method of melting and kneading at ℃ can be adopted.

[Use] The resin composition of the present invention has excellent drawdown resistance and is suitable for blow molding because the gloss of a blow molded product can be suppressed to a low level. Particularly, it is suitable for large blow molding having a parison weight of 1 kg or more. It can be suitably used. In addition, since it has such features, it can be applied to exterior parts such as automobile parts, home electric appliance parts, and housing equipment parts, and is particularly suitably used for interior and exterior parts of automobiles such as instrument panels and bumpers of automobiles. Can be.

[0019]

EXAMPLES The present invention will be described in further detail with reference to Examples. The test methods used in the examples are as follows. (1) Melt flow rate (MFR) Determined in accordance with JIS K-6758. For a polypropylene resin, the measurement was performed at 230 ° C. under a load of 2.16 kgf.
It measured under the condition of a load of 2.16 kgf.

(2) Drawdown resistance Using a hollow molding machine having a die diameter of 100 mmφ and an accumulator capacity of 25 liters, a parison having a resin temperature of 225 ° C. and a parison length / weight = 1700 mm / 9 kg was completed 5 seconds after the completion of injection. The change in parison length was measured and L / L
₀ <1.20 was evaluated as good (○), and unsatisfied was evaluated as poor (x). L: parison length 3 seconds after the end of injection L ₀ : parison length at the end of injection

(3) Gloss evaluation Using a hollow molding machine having a die diameter of 60 mmφ and an accumulator capacity of 1 liter, a resin temperature of 235 ° C. and a mold temperature of 80
A 1 liter square bottle was molded at a temperature set to ° C. One side of the above-mentioned square bottle mold was smooth and the other side was grained, and the gloss of each of the obtained molded articles was measured. The gloss value (unit:%) is JIS K-
Sample number n = 3 based on 7105 (angle 60 degrees)
The same part of each surface was measured by using, and the average value was obtained.

Example 1 (a) As a polypropylene resin, a propylene-ethylene block copolymer having an MFR of 0.35 g / 10 min and an ethylene content of 5 % by weight (IDEMITSU PP E-185G manufactured by Idemitsu Petrochemical Co., Ltd.) "PP-1"
65 kg) and (b) polyethylene resin,
High-density polyethylene with MFR of 0.03 g / 10 min and density of 0.95 g / cm ³ (IDEMIT manufactured by Idemitsu Petrochemical Co., Ltd.)
SU HDPE 750LB) ("PE-1") 15kg,
(C) 20 k of talc having an average particle size of 4 μm as an inorganic filler
g, (d) No rubbery polymer was added, and (e) 1,3-bis- (t-butylperoxyisopropyl) benzene as an organic peroxide was mixed in a tumbler mixer using 0.01 kg. The mixture was granulated at a kneading temperature of 220 ° C. in a twin-screw kneading extruder at a rotor rotation speed of 700 rpm and an orifice opening of 60%. Using the obtained pellets, the above-described drawdown resistance was evaluated, and further the gloss was evaluated. Table 1 shows the evaluation results.

Example 2 In Example 1, (a) the polypropylene resin was changed from 65 kg to 55 kg,
(B) Pellets were prepared in the same manner except that the polyethylene resin was changed from 15 kg to 25 kg, and the drawdown resistance and gloss were evaluated. Table 1 shows the evaluation results. Example 3 Pellets were prepared in the same manner as in Example 2 except that (e) the organic peroxide was changed from 0.01 kg to 0.02 kg, and the drawdown resistance and the gloss were evaluated. . Table 1 shows the evaluation results.

Example 4 In Example 2, (b) the polyethylene resin was changed from 25 kg to 20 kg, and (d)
Mooney viscosity (ML _{1 + 4} , 100
C) 70 ethylene-propylene rubber (manufactured by JSR,
Pellets were prepared in the same manner except that 5 kg of EP07P) was newly added, and the drawdown resistance and the gloss were evaluated. Table 1 shows the evaluation results.

Comparative Example 1 Pellets were prepared in the same manner as in Example 1 except that (e) the organic peroxide was not added, and the drawdown resistance and the gloss were evaluated.
Table 1 shows the evaluation results. [Comparative Example 2] In Example 1, (a) a propylene-ethylene block copolymer having an MFR of 0.35 g / 10 minutes and an ethylene content of 5% by weight (IDEMITSU PP E-185G manufactured by Idemitsu Petrochemical Co., Ltd.) (PP-
From 1), a propylene-ethylene block copolymer having an MFR of 1.5 g / 10 min and an ethylene content of 5% by weight (IDEMITSU PP E-250GX manufactured by Idemitsu Petrochemical Co., Ltd.) (“PP-
2)), except that the pellet was prepared in the same manner,
The drawdown resistance and the gloss were evaluated. Table 1 shows the evaluation results. Comparative Example 3 Pellets were prepared in the same manner as in Example 1 except that (e) the organic peroxide was changed from 0.01 kg to 0.25 kg, and the drawdown resistance and the gloss were evaluated. . Table 1 shows the evaluation results.

[0026]

[Table 1]

[0027]

According to the present invention, as shown in Examples 1 to 4, both the drawdown resistance and the gloss are excellent and excellent. On the other hand, in the prior art represented by Comparative Example 1, the drawdown resistance is good, but the gloss is inferior to both flat and grained surfaces. Further, as shown in Comparative Example 2, when the MFR of the polypropylene resin as the base resin is larger than a predetermined value, the drawdown resistance is inferior and molding is impossible. Further, as shown in Comparative Example 3, when the amount of the organic peroxide added is larger than the predetermined upper limit, the drawdown resistance is also inferior and molding is impossible.

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Claims (5)

[Claims] 1. A polypropylene resin having a melt flow rate (MFR) of 0.1 to 1 g / 10 min.
99% by weight, (B) a polyethylene resin 1 having a melt flow rate (MFR) of 0.01 to 0.5 g / 10 min.
-40% by weight, (C) 0-30% by weight of inorganic filler,
(D) 0 to 30% by weight of the rubbery polymer and (E) 0.001 parts by weight of the organic peroxide with respect to 100 parts by weight of the total of the above components (A), (B), (C) and (D). A propylene-based resin composition for blow molding, which is prepared by mixing and melt-kneading a mixture of about 0.2 parts by weight. 2. The propylene resin composition for blow molding according to claim 1, wherein the polypropylene resin as the component (A) has an ethylene content of 1 to 30% by weight. 3. A polyethylene resin having a density of 0.
The propylene-based resin composition for blow molding according to claim 1 or 2, which is a high-density polyethylene having a content of 940 g / cm ³ or more. 4. The parison weight in blow molding is 1 kg.
The propylene-based resin composition for blow molding according to any one of claims 1 to 3, which is the above. 5. Interior and exterior parts for automobiles blow-molded using the propylene-based resin composition for blow molding according to claim 1.