JPH10230543A - Tubular blow-molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity of a blow-molded article having flexibility and rigidity by a method wherein specified polypropylene resin having flexibility is employed at the flexible structural part of an air duct or a joint part. SOLUTION: A material employing at a flexible part is a block copolymer, in which the copolymer component of ethylene-propylene follows to the homopolymer component of propylene. When the limiting viscosity of the homopolymer component is denoted by [η]PP, that of the copolymer component by [η]RC, the weight of the homopolymer component by WPP and that of the copolymer component by WRC, the product of the ratio of the limiting viscosities of the copolymer component and of the homopolymer component and the ratio of the weights of the homopolymer and of the copolymer: [([η]RC/[η]PP)×(WPP /WRC)] lies in the range of 0.2-2.0. Further, the ratio of the MFR (230 deg.C; 21.18N) of the homopolymer component to that of the copolymer comp component lies in the range of 0.3-4.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow molded article using a polypropylene resin, and more particularly, to heat resistance, flexibility, weld properties, and impact resistance whitening using a polypropylene resin having good moldability. The invention relates to ducts and joint parts such as industrial parts which are extremely excellent in hollow molded products.

[0002]

2. Description of the Related Art Polypropylene resins are widely used in blow-molded hollow moldings because of their excellent properties such as rigidity, impact resistance, heat resistance, hygiene, and moldability. Hollow molded products of polypropylene resin, especially air ducts, do not fully satisfy the market requirements for heat resistance and flexibility to facilitate workability. It was a very important task. As a specific example, Japanese Patent Application Laid-Open No. 52-126450 reports a flexibility improving technique in which 50 to 90% by weight of an ethylene-α-olefin copolymer rubber is blended with polypropylene or high-density polyethylene. In Japanese Utility Model Laid-Open No. 4-282232, it is reported that flexibility and sag resistance are excellent by using a styrene-based thermoplastic elastomer made of polystyrene and hydrogenated polybutadiene or hydrogenated polyisoprene for a flexible portion of a resinous tubular body. ing. In the literature (Plastics, Vol.44, No.11, P-31), a duct hose having a bellows structure in which the elastomer component of the TPE composition is adjusted so as to have the characteristics of the elastomer and the function of a hollow molded article is provided. For example, there have been reports of examples of use for air intake hoses, air flow ducts, connector pipes, and the like, or examples of using TPE for an arbitrary bellows structure portion and using polypropylene resin having excellent rigidity for other portions. However, the raw material price of the TPE resin composition having such elastomer characteristics is high. In terms of performance, the required characteristics are not necessarily satisfied, such as a decrease in the pinch-off strength of the weld portion or the mold cutout portion and an adverse effect on recyclability.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hollow molded article having a rigid portion and a flexible portion, while taking advantage of the many excellent properties of propylene, while having a flexibility that cannot be obtained with conventional polypropylene. Providing a hollow molded product with flexibility and rigidity with good productivity by blow molding method by using the polypropylene resin of the above for the flexible structure of the air duct or joint part and using the conventional polypropylene resin composition for the rigid part And to facilitate recyclability by using similar materials.

[0004]

The present invention comprises the following "basic structure", "improved structure 1" and "improved structure 2": "basic structure" comprising a highly rigid portion (A) and a flexible portion (B). In the hollow molded article having a duct or hose shape, the material used for the flexible portion (B) is a block copolymer consisting of a propylene homopolymer component followed by an ethylene-propylene copolymer component, and the intrinsic viscosity of the homopolymer component [ η] Intrinsic viscosity of PP and copolymer component [η]
When the weight of RC and its homopolymer component and the weight of the copolymer component are W _PP and W _RC , respectively, the product of the ratio of the intrinsic viscosity of the copolymer component to the homopolymer component and the weight ratio of the homopolymer component to the copolymer component [([[ η] RC / [η]
PP) × (W _PP / W _RC )] is in the range of 0.2 to 2.0,
The ratio of the MFR of the homopolymer component (230 ° C .; 21.18N) to the MFR of the copolymer component (230 ° C .; 21.18N) is in the range of 0.3 to 4.0, and the [η] RC of the copolymer component is 6. A propylene-based block copolymer composition (C) having a flexibility of not more than 5 and an MFR (230 ° C .; 21.18N) of 0.1 to 4 g / 10 min is provided with a duct or hose-shaped flexible structure or bellows structure. A cylindrical hollow molded product obtained by a connected parison method, wherein the high rigid portion (A) is made of a polypropylene composition having excellent heat resistance and rigidity.

A propylene-based block copolymer composition (C) characterized by the flexibility described in the "improved constitution 1" basic constitution.
MFR (190 ° C; 21.
MFR (230 ° C; 21.18N) comprising 20 to 0 parts by weight of one or more olefin polymers selected from the following groups (D1) to (D2) having an NFR of 0.1 to 5 g / 10 min. An olefin-based resin composition (E) having a flexibility of 4 g / 10 min is used for a duct or hose-shaped flexible structure or bellows structure, and a high-rigidity portion (A) is made of a polypropylene composition having excellent heat-resistant rigidity. Cylindrical hollow molded article obtained by the concatenated parison method. D1: an ethylene crystalline polymer having an MFR (190 ° C .; 2
1.18N) 0.1-5g / 10min, density 0.910-0.930g /
An ethylene polymer having a cm ³ and a crystal melting point (Tm) of 100 to 115 ° C. D2: ethylene-vinyl acetate copolymer with MFR
(190 ° C; 21.18N) 0.1-5g / 10min, density 0.920
0.935 g / cm ³ , crystal melting point (Tm) 90-108 ° C., vinyl acetate content 1-10% by weight.

"Improved structure 2" A flexible structure obtained by a blow molding method comprising the propylene-based block copolymer composition (C) or the olefin-based resin composition (E) described in the basic structure or the improved structure 1 or Air ducts, air hoses, and joint parts having flexibility as a bellows structure and functionality as a cylindrical hollow molded product.

The present invention will be described in detail below. Constitutive characteristics of the propylene-based block copolymer composition (C) used in the present invention is a relational expression [([η] RC / [η] PP) × of the homopolymer component and the copolymer component and the intrinsic viscosity.
(W _PP / W _RC )] is in the range of 0.2 to 2.0, more preferably in the range of 0.3 to 1.9, and the homopolymer component M
FR (230 ° C; 21.18N) and MFR of the copolymer component (230 ° C; 2
1.18N) in the range of 0.3 to 4, more preferably 0.3 to 4.
The intrinsic viscosity [η] R of the copolymer component is in the range of 3.5.
C is 6.5 or less, more preferably 5.0 or less, and the propylene-based block copolymer composition has an MFR (230
C .; 21.18N) is 0.1 to 4 g / 10 min, preferably 0.3 to 2 g.
/ 10min. The propylene copolymer composition in the above range has excellent hollow moldability, flexibility and impact whitening resistance. Outside the above range, for example, the relational expression [([η] RC /
[Η] PP) × (W _PP / W _RC )] is a hollow container molded using a propylene-based block copolymer composition having a value outside the range of 0.2 to 2.0. The effect of improving the impact whitening property is insufficient. If the MFR (230 ° C; 21.18N) is 0.1g / 10min or less, the melt viscosity is high and the motor load is large, and the productivity of the hollow container is inferior. If the MFR is 4g / 10min or more, the drawdown is large and the rigidity decrease due to uneven wall thickness is large. It cannot meet the characteristics of molded articles.

The content of each of the above components is preferably in the range of 30 to 70% by weight of the copolymer component.
More preferably, it is in the range of 40 to 60% by weight. If the composition is out of the above range, impact whitening property and bending whitening property are insufficient, and rigidity and flexibility deviate from practical characteristics. In particular, when the content is less than 30% by weight, flexibility is insufficient, and
A hollow molded article using a composition exceeding the weight% has a low rigidity and cannot satisfy the function as a hollow molded article.

The copolymer component has an ethylene content of 25 to
75% by weight, preferably 30-60% by weight
Range. When the ethylene content of the copolymer component is 25
If the content is less than 75% by weight, the impact resistance is insufficient, and if it is more than 75% by weight, the pinch-off property and the weld property of the hollow molded article are not excellent.

The MFR (230 ° C .; 21.18N) of the propylene-based block copolymer composition (C) used in the present invention is 0.1% in terms of the productivity and moldability of a hollow molded article using the composition. 1
４4 g / 10 min, more preferably 0.3 to 2 g / 10 min.
min. Suitable propylene-based block copolymers (C) are first produced from a crystalline homopolypropylene component, the intrinsic viscosity [η] _PP and the MFR of the polymer component.
(230 ° C .; 21.18N) [MFR _PP ] is measured directly. Subsequently, the intrinsic viscosity [η] of the copolymer component, which is a propylene-ethylene random copolymer produced, is determined by _RC and MFR (230
° C; 21.18N) [MFR _RC ] cannot be measured directly.

[0011] Therefore the copolymer composition overall intrinsic viscosity [eta] _WHOLE measured, the intrinsic viscosity [eta] _WHOLE of the total composition
Is obtained by multiplying the weight fraction of the homopolypropylene component by the intrinsic viscosity [η] _PP of the homopolypropylene component, and dividing this by the fraction of the total composition, that is, the copolymer component, to obtain the intrinsic viscosity of the copolymer part [η]. _RC is required. That is, it is obtained from the following (Equation 1).

[0012]

Embedded image

The MFR of the copolymer component (230 ° C .; 21.
18N) [MFR _RC ] is obtained by measuring the MFR (230 ° C .; 21.18N) [MFR _PP ] of the entire copolymer composition and homopolypropylene, and is obtained from the following (Formula 2).

[0014]

Embedded image

Wherein the fraction of the copolymer component [W _RC / 100]
Can be determined by a conventionally known infrared analysis method or the like. The propylene-based block copolymer composition (C) used in the present invention may be obtained by any method.
For example, a blend of homopolypropylene and an ethylene-propylene low-crystalline copolymer (hereinafter abbreviated as EPR) having an intrinsic viscosity ratio defined in the present invention may be used.
Further, a blend in which an ethylene-propylene random copolymer polymerized using a titanium-containing solid catalyst component is added to homopolypropylene may be used.

However, the method of blending EPR is disadvantageous in terms of economy, such as the high price of EPR and the necessity of a blending step. Further, the method of blending EPR has a problem that quality cannot be stabilized due to poor dispersion. A preferred method for obtaining the propylene-based block copolymer of the present invention is a method for producing by a polymerization. The propylene-based block copolymer composition (C) of the present invention obtained by polymerization is preferable because it does not require EPR and is inexpensive, and a stable product can be obtained.

Hereinafter, a production method by polymerization will be exemplified. The production method of the propylene-based block copolymer (C) of the present invention by polymerization is carried out in the presence of a titanium-containing solid component, an organoaluminum compound and, if necessary, an electron donor in a small amount of olefin per gram of the titanium-containing solid catalyst component. 0.1
To 100 g, and then main polymerization of propylene in the presence of an organoaluminum and, if necessary, an electron donor in the presence of the preactivated catalyst, followed by propylene and ethylene And obtaining a powder of a propylene-based block copolymer by random copolymerization.

As the titanium-containing solid catalyst in the above-mentioned method for producing a propylene-based block copolymer, any known titanium-containing solid catalyst supported on a magnesium compound can be used. For example, spraying a magnesium compound-alcohol solution, partially drying the solid component,
Thereafter, the dried component is treated with a titanium halide and an electron donating compound to obtain a titanium-containing solid catalyst component (Japanese Patent Application Laid-Open No.
No. 119003). Also, a titanium-containing solid catalyst component obtained by dissolving a magnesium compound in tetrahydrofuran / alcohol / electron donor and treating magnesium alone precipitated by TiCl ₄ alone or in combination with an electron donor with titanium halide and an electron donating compound. (JP-A-4-103604).

The organoaluminum compound used in the polymerization of the present invention has a general formula of AlR ⁵ MR ⁶ NX _{3- (M + N)} (wherein R ⁵ and R ⁶ represent a hydrocarbon group or an alcohol group;
Represents a halogen, and M and N represent an arbitrary number satisfying 0 <M + N ≦ 3. ) Can be used. Specifically, trimethyl aluminum,
Triethyl aluminum, tree n-propyl aluminum, tree n-butyl aluminum, tree i-butyl aluminum, dimethyl aluminum chloride, emethyl aluminum chloride, methyl aluminum sesquichloride, di-n-propyl aluminum monochloride, ethyl aluminum sesquichloride, ethyl aluminum Examples thereof include dichloride, diethylaluminum iodide, and ethoxydiethylaluminum. These organoaluminum compounds can be used alone or in combination of two or more.

The electron donor used in the polymerization of the present invention may be represented by the general formula R ² XR ³ YSi (OR ⁴ ) Z (wherein R ²
X and R ⁴ represent a hydrocarbon group; R ³ represents a hydrocarbon group or a hydrocarbon group containing a hetero atom; X + Y + Z = 4, 0 ≦ X
Organic compounds represented by ≦ 2, 1 ≦ Y ≦ 3, and 1 ≦ Z ≦ 3 can be used.

Specifically, methyltrimethoxysilane, t
-Butyltrimethoxysilane, t-butyltriethoxysilane, phenyltriethoxysilane, methylethyldimethoxysilane, methylphenyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane,
Examples thereof include diisopropyldimethoxysilane, diisobutyldimethoxysilane, di-tert-butyldimethoxysilane, diphenyldimethoxysilane, trimethylmethoxysilane, and trimethylethoxysilane. Preferred are diisobutyldimethoxysilane, diisopropyldimethoxysilane, di-tert-butyldimethoxysilane and diphenyldimethoxysilane. These organosilicon compounds can be used alone or in combination of two or more. The polymerization of propylene in the production of the homopolypropylene component of the propylene-based block copolymer of the present invention may be any of a slurry polymerization method, a bulk polymerization method and a gas phase polymerization method using the above-mentioned titanium-containing solid catalyst or the like. ,
A gas phase polymerization method is preferable for the polymerization method of the copolymer component in the latter stage. In a slurry polymerization method or a bulk polymerization method, a copolymer component is eluted in a solution, and it is difficult to continue stable operation, and the effect of the present invention is not sufficiently exhibited. The improvement effect of the present invention is remarkable in a combination of gas phase polymerization and gas phase polymerization.

The polymerization conditions vary depending on the polymerization method. In the case of the gas phase polymerization method, the polymerization pressure is 20 to 120 ° C., preferably 40 to 100 ° C., and the polymerization pressure is atmospheric pressure to 10 MPa.
Preferably, propylene is supplied under the conditions of 0.5 to 5 MPa to polymerize the homopolymer component. It is effective to adjust the molecular weight of the homopolymer component by adding a molecular weight modifier such as hydrogen during polymerization. Subsequent to the polymerization of the homopolymer component, the copolymer component is polymerized at a polymerization temperature, usually 20 to 120 ° C, preferably 40 to 100 ° C, at a polymerization pressure of atmospheric pressure to 1
Polymerization under the conditions of 0 MPa, preferably 0.5 to 5 MPa produces a propylene-based random copolymer.
The ethylene content in the copolymer component of the present invention is adjusted such that the ethylene content in the copolymer component becomes 25% by weight to 65% by weight by controlling the gas molar ratio of the ethylene monomer and the propylene monomer in the comonomer gas. The weight of the copolymer component with respect to the weight of the homopolymer component is adjusted so that the weight of the copolymer component becomes 30 to 80% by weight by controlling the polymerization time or using a polymerization activity regulator such as carbon monoxide or hydrogen sulfide. Adjusted. Further, the molecular weight of the copolymer component is adjusted during the copolymerization of a copolymer by adding a molecular weight modifier such as hydrogen so that the intrinsic viscosity and MFR of the copolymer component meet the requirements of the present invention. The polymerization may be any of a rotary system, a semi-continuous system, or a continuous system, but industrially, a continuous polymerization is preferable.

The resin (D) to be blended with the propylene block copolymer (C) of the present invention is an ethylene crystalline polymer as described in detail below: The crystalline ethylene polymer (D1) has a density of 0.910-0 / 930 g / cm ³ , crystal melting point 100-115 ° C, MFR (190 ° C; 21.18N) 0.1-0.1
The crystalline ethylene polymer is 5 g / 10 min, preferably 0.1 to 1 g / 10 min, and is produced by a high-pressure method using peroxide as a catalyst. It is usually called low density polyethylene. Crystalline ethylene polymer (D2) a density of ^{0.920~0.935g / cm 3, MFR (190} ℃; 21.1
8N) is 0.1 to 5 g / 10 min, and vinyl acetate content is 1 to 1
0% by weight of ethylene-vinyl acetate copolymer (Ethylene V
inylacetate Copolymer) (hereinafter abbreviated as EVA)
Preferably, the vinyl acetate content is 2 to 5% by weight, and the MFR (190 ° C; 21.18N) is 0.1 to 0.1% by weight.
1 g / 10 min is preferred. The EVA is a crystalline ethylene copolymer obtained by radical copolymerizing ethylene and vinyl acetate in the presence of an organic peroxide or oxygen. A crystalline ethylene polymer satisfying the above properties is sufficient as the moldability improving effect of the present invention, and the resin (B1
To B2) may be used alone or in combination of two or more. The compounding amount can be arbitrarily selected depending on the size or shape of the molded article, and a molded article with less uneven thickness due to improvement in moldability can be obtained in the range of 0 to 20 parts by weight or less. If the amount exceeds 20 parts by weight, the pinch-off strength and heat resistance of the mold cut-out portion decrease, and the object of the present invention cannot be satisfied.

The propylene block copolymer composition (C) and the olefin polymer composition (E) used in the hollow molded container of the present invention contain an acid inhibitor, a weathering agent, an ultraviolet absorber,
An antistatic agent, a colorant, a crystal nucleating agent, an olefin-based elastomer and a polypropylene homopolymer, an ethylene-propylene crystalline random copolymer, a high-density polyethylene and the like can be blended within a range that does not impair the object of the present invention. The hollow molded article or the air duct and the joint part comprising the resin composition of the present invention thus obtained can obtain hollow molded articles having extremely excellent flexibility and functionality.

The resin composition of the present invention can be obtained by mixing the above-mentioned components as required. For mixing these components, for example, a mixer with a high-speed stirrer such as a Henschel mixer (trade name) or a super mixer (trade name), a usual mixing device such as a ribbon blender or a tumbler, and a single screw extruder as a melt kneading device. Alternatively, a twin screw extruder or the like is used. The kneading temperature is generally from 200 to 300C, preferably from 220 to 270C.

The polypropylene composition having excellent heat resistance and rigidity used for the high rigidity part (A) has an ethylene component of 30%.
5 to 15 parts by weight of an elastomer composition comprising 70 to 30% by weight and 70 to 30% by weight of a propylene component is an impact-resistant polypropylene having a density of 0.90 to 0.91 g / cm ³ , which has a density of 0.90 to 0.91 g / cm ³ , which is block-bonded to a propylene chain (230 ° C; 21.17
N) is 0.3 to 4 g / 10 min, preferably 0.5 to 1.6 g / 10 m
Examples of in include those having a molecular weight distribution of 5 to 12. Melt flow rate (230 ° C; 21.17N) is 0.1
If it is less than 3 g / 10 min, the melt viscosity is large, so that the productivity is greatly reduced. If it is more than 4 g / 10 min, the drawdown property is large and the moldability is extremely difficult. Further, if the material has a molecular weight distribution within the above range, it can be used as a hollow molding material without productivity or occurrence of melt fracture. The polypropylene composition used for the high-rigidity portion (A) may contain an inorganic filler such as talc, calcium carbonate, calcium silicate or the like having an average particle diameter of 10 μm or less for the purpose of imparting heat-resistant rigidity. You may mix | blend in the range which does not impair performance, and generally 20 weight% or less.

The hollow molded product having a duct or hose shape composed of the highly rigid portion (A) and the flexible portion (B) according to the present invention uses an accumulator type hollow molding machine having two or more extruders. Supplying the propylene-based block copolymer composition (C) or the olefin polymer composition (E) of the present invention to an extruder for flexibility, and a polypropylene composition having excellent heat resistance and rigidity to an extruder for high rigidity; An example is a blow molding method of a connected parison method in which a material is switched at a site suitable for the purpose of a molded product. That is, the hollow molded article of the present invention is excellent in heat resistance and rigidity from a flexible propylene block copolymer composition (C) or a rigid olefin polymer composition (E) from an extruder for flexibility. A connected parison for supplying a polypropylene composition from a high-rigidity extruder to a die having two or more layers, and switching a supply resin at a die head portion so as to conform to a portion of the molded product requiring flexibility or rigidity. It extrudes. These molten parisons may be blow-molded molds maintained at a temperature of 60 ° C. or less, or may be provided with a bellows structure as required in order to increase the flexibility of the flexible propylene-based block copolymer composition (C). A parison is installed in the mold and pressurized air (0.5 to 1MP
A molding method in which a) is blown to apply air pressure until the shape is fixed can be exemplified. In addition, depending on the layer configuration of the molding machine, a gas barrier layer may be provided on the inner layer via an adhesive layer.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited by these specific examples. The characteristics used in the following Examples and Comparative Examples were evaluated by the following methods.

[0029]

【Example】

(1) 230 ° C. melt flow rate (abbreviated MFR):
Test conditions 14 (2) of JIS K7210 (1976)
30 ° C, 21.18N) (unit: g)
/ 10min). (2) 190 ° C melt flow rate (abbreviation: MFR-
): Test condition 1 of JIS K7210 (1976)
4 (190 ° C., 21.18 N) (unit: g / 10 min) (3) Intrinsic viscosity [η]: The temperature is determined for the polymer, and the polymer in the solvent given is in an extremely diluted state. Mean viscosity at the time. In the case of the present invention, the viscosity was determined at 135 ° C. using tetralin (tetrahydronaphthalene) as a solvent and using an automatic viscosity meter AVS2 manufactured by Mitsui Toatsu Co. (unit: dl / g).

(4) Impact whitening resistance: A hollow molded article is laid horizontally in an environment of 20 to 25 ° C., and a striker (190 g) having a tip radius of 6.35 mm is applied to the molded article (portion using a flexible material). , A load of 500 g was dropped onto the shooting core from a height of 50 cm, and the diameter of the whitened surface generated around the shooting core was measured. A: Scratches are seen in the hammer but no whitening is seen. B: Whitening of 8 mmφ or less occurs in the striker portion. C: Whitening of 8 to 15 mmφ occurs in the hammer portion. D: Whitening of 15 mmφ or more occurs in the hammer portion.

(5) Formability: A molten parison is extruded at a molding temperature of 200 ° C., a screw diameter of 50φ, and a screw rotation speed of 40 rpm (a die diameter of 21 mm and a core diameter of 19 m).
m) The speed at which the parison hangs down to 12 cm and 50 cm is measured, and the difference between the two hang speeds is determined based on the difference (speed up to 50 cm / speed up to 12 cm). A: A material having a small drawdown and a speed difference of 5% or less. B: A material having a drawdown speed difference of 5 to 20%. C: A material having a drawdown speed difference of 20% or more (defective molding). (6) Flexibility: A hollow molded product (60φ) in a room at 23 ± 2 ° C
× 300 × 1.6mm ^t / 7 pitch bellows structure in the center,
One end of a pitch of 10 mm and a groove depth of 10 mm) is fixed, and the amount of deformation when a load of 1 kg is applied to one end is determined by an angle. A: It has a deformation amount of 30 degrees or more. B: Deformation amount of 20 degrees or more and less than 30 degrees. C: Deformation amount of 10 degrees or more and less than 20 degrees. D: Deformation less than 10 degrees.

(7) Strength of connecting part: A test piece is cut out from the resin switching part of the molded product, and the tensile strength is measured. A: It has a strength equal to or higher than that of the flexible resin to 95% or more. B: A flexible resin having a strength of 95 to 80%. C: strength less than 80% of the flexible resin. (8) Heat resistance: The molded product was placed in an oven at 150 ° C. for 100 hours.
Evaluation of deformation and appearance when left for a long time. A: No deformation or abnormal appearance is observed. B: Dimensional change is 2% or less, and almost no change in appearance is observed. C: Appearance change (deterioration) is observed when the dimensional change is 2% or more.

The polymers and fillers used in the following Examples and Comparative Examples are abbreviated as follows. PP1: [η] RC / [η] PP × W _PP / W _RC = 1.7, M
FR _PP / MFR _RC = 1.4, [η] RC of copolymer component
= 3.0, MFR of polymer (230 ° C .; 21.18N) = 0.68 g /
10 min propylene block copolymer composition (polymer of Example 1). PP2: [η] RC / [η] PP × _WPP / _WRC = 7.5, M
FR _PP / MFR _RC = 42.2, [η] R of copolymer component
C = 2.2, MFR of polymer (230 ° C .; 21.18N) = 2.0 g / 1
0 min propylene block copolymer composition (Comparative Example 3
Polymer).

PP3: MFR 0.65 g / 10 min, ethylene content 7.5 wt%, ethylene content in the copolymer component 59 wt%, weight of the copolymer component 12.7 wt%, flexural modulus 1,100 MPa, crystal melting point 165 ° C. Ethylene-propylene block copolymer. PP4: 1 talc having an average particle size of 1.6 μm was added to PP3.
A material blended with 0 wt% and having an MFR of 0.72 g / 10 min, a density of 0.96 g / cm ³ , a flexural modulus of 2,100 MPa, and a crystal melting point of 165 ° C. (Talc has a specific surface area of 44,000 cm ² /
g. A component having an average particle size of 1.6 μm and a particle size of 10 μm or more.
5 wt%, MgO component 33.1 wt%, SiO ₂ component 62.
5% by weight, 0.3% by weight of Fe ₂ O ₃ component and 0.1% of CaO component
5% by weight). PE1: MFR = 0.4 g / 10 min, crystal melting point (Tm) =
Low-density polyethylene having a density of 0.920 g / cm ³ at 110 ° C. PE2: MFR = 0.5 g / 10 min, crystal melting point (Tm)
= An ethylene vinyl acetate copolymer having a density of 0.925 g / cm ³ and a bunyl acetate content of 3% by weight.

(Examples 1 to 12 and Comparative Examples 1 to 10) The olefin resin composition of the present invention was prepared by mixing 100 parts by weight of polypropylene as the base resin body, and the basic stabilizer formulation was Tris ( 0.05 parts by weight of 2,4-di-t-butylphenyl) phosphite, tetrakis [methylene (3,
5-di-t-butyl-4-hydroxyhydrocinnamate)]
0.15 parts by weight of methane and 0.1 part by weight of calcium stearate are blended, if necessary, a low-density polyethylene resin is blended as a blended resin, and mixed using a Henschel mixer, and the extruder is set to 250 ° C. The mixture was melt-kneaded and extruded to obtain a pellet-shaped composition.

The pellet-form composition was put into a flexible extruder of a hollow molding machine having two extruders, and the polypropylene composition having excellent heat resistance and rigidity was put into a rigid extruder.
The resin melted at 200 ° C. is individually supplied to the two-layer die head, and a connected parison in which the supply of the flexible resin and the rigid resin is switched according to the purpose of the molded product is extruded.
Blown into a mold (60φ × 300
× 1.6mm ^t / 7 pitch bellows structure at center, pitch 10m
m, groove depth 10 mm, average thickness of bellows 0.9 mm ^t )
Molded. In addition, it adjusted so that soft resin might come to a bellows part. The properties of the hollow molded product are shown in Tables 1 to 3.

In Examples 1 to 8 shown in Table 1, the propylene-based block copolymer composition of the present invention, that is, a block copolymer comprising a propylene homopolymer component followed by an ethylene-propylene copolymer component was added to the flexible portion of the hollow molded article. In the polymer, the intrinsic viscosity [η] PP of the homopolymer component and the intrinsic viscosity [η] RC of the copolymer component, and the weight of the homopolymer component and the weight of the copolymer component are W _PP and W, respectively.
_{When RC} , the product of the intrinsic viscosity ratio of the copolymer component and the homopolymer component and the weight ratio of the homopolymer component and the copolymer component [([η] RC / [η] PP) × (W _PP / W _RC )] M in the range of 0.2 to 2.0 and the homopolymer component
FR (230 ° C; 21.18N) and MFR of the copolymer component (230 ° C; 2
1.18N) in the range of 0.3 to 4.0, the [η] RC of the copolymer component is 6.5 or less, the ethylene content in the copolymer component is 25 to 65% by weight, and the weight of the copolymer component is 25 to 65% by weight. 30-70% by weight, MFR (230 ° C; 21.18N) 0.1-4g
Propylene-based block copolymer obtained as a gas-phase polymer in 10 min., And PP3 (MFR 0.65 g / 10 min.,
A blow molding method for switching molten resin in a die head using a density of 0.901 g / cm ³ , an ethylene content of 7.5 wt%, and a flexural modulus of 1,100 MPa (generally called connection blow or exchange blow molding). )
Is a hollow molded product obtained by the method described above. Moldability, heat resistance,
A hollow molded product having a part with excellent weld strength, good joint strength between a high rigidity part and a flexible part, and excellent flexibility was obtained.
In particular, since a flexible part having a large deformation is excellent in impact whitening property, it is a hollow molded article having excellent commercial value in function and appearance without causing whitening due to bending or the like.

On the other hand, in Comparative Examples 1 to 8 shown in Table 2, a propylene-based block copolymer composition deviating from the invention of the present application was used for a flexible portion of a hollow molded article. The product of the intrinsic viscosity ratio of the components and the weight ratio of the homopolymer component and the copolymer component [([η]
RC / [η] PP) × (W _PP / W _RC )] is 2 or more, resulting in inferior impact whitening resistance, and whitening also occurs due to bending. In Comparative Examples 1, 2, 3, and 8, the copolymer component was 30% by weight or less, and the flexibility which is the object of the present invention could not be obtained. In Comparative Examples 3, 5, 6, and 7, the ratio of the MFR (230 ° C .; 21.18N) of the homopolymer component to the MFR (230 ° C .; 21.18N) of the copolymer component greatly exceeded 4, so that the impact whitening property was high. In addition, whitening occurs due to bending, and commercial value cannot be satisfied. Further, Comparative Example 7
FR _WHOLE is high, the uniformity of the product thickness is reduced, and the performance as a blow molded product cannot be satisfied. Examples 9 to 11 shown in Table 3 are olefin polymers (ethylene-based polymer, PE1 or PE1) as the resin of the present invention and the propylene-based block copolymer shown in Example 1 and the compounded resin.
2) The performance (functionality,
Appearance) was extremely excellent, and the drawdown property and thickness uniformity during molding were improved.

In Examples 12 and 13, a resin (PP4) in which talc was filled in a highly rigid portion was used. Excellent joint strength, performance of hollow molded product (functionality, appearance)
Are also excellent hollow molded articles. In Comparative Examples 9 and 10, a large amount of a propylene-based block copolymer (the polymer of Example 1 and the polymer of Comparative Example 3) was blended in the flexible portion and an olefin polymer (ethylene-based polymer: PE1, PE2) was blended in a large amount with the blended resin. Things. Although the flexibility, impact whitening property, moldability, etc. are good, the weld properties, the strength of the joints, the decrease in heat resistance, etc. occur, and the performance as a hollow molded article, which is the object of the present invention, cannot be satisfied. Comparative Example 11 uses an olefin polymer (PE1) for the flexible portion.
Excellent in moldability, impact whitening property, flexibility, etc., but poor in heat resistance and bonding strength with ethylene-propylene block copolymer (PP3) used for high rigidity parts, hollow molded article which is the object of the present invention Performance cannot be satisfied.

[0040]

According to the present invention, the hollow molded article comprising a high rigidity part and a flexible part obtained by the present invention is made of a polypropylene resin in any part, has an extremely excellent connection strength between the two resins, has good moldability, and is recyclable. It is possible to obtain a hollow molded product having excellent resilience and suitable for a device requiring free deformation at the time of vibration absorption or assembling, such as an intake duct of an automobile part.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takanori Nakajima 8890 Goi, Ichihara-shi, Chiba

Claims (3)

[Claims] In a hollow molded article having a duct or hose shape comprising a highly rigid portion (A) and a flexible portion (B), the material used for the flexible portion (B) is propylene homopolymer component followed by ethylene-propylene. Wherein the intrinsic viscosity [η] PP of the homopolymer component and the intrinsic viscosity [η] RC of the copolymer component and the weight of the homopolymer component and the weight of the copolymer component are W _PP and W, respectively. _{When RC} , the product of the intrinsic viscosity ratio of the copolymer component and the homopolymer component and the weight ratio of the homopolymer component and the copolymer component [([η] RC /
[Η] PP) × (W _PP / W _RC )] is in the range of 0.2 to 2.0, and the MFR of the homopolymer component (230 ° C .; 21.18N) and the MFR of the copolymer component (230 ° C .; 21.18 N) N) is 0.3-
4.0, and [η] RC of the copolymer component is 6.5.
The propylene-based block copolymer composition (C), which has a MFR (230 ° C .; 21.18N) of 0.1 to 4 g / 10 min below, is characterized by a duct or hose-shaped flexible structure or bellows structure. And a hollow hollow molded article obtained by a connected parison method, wherein the high-rigidity portion (A) is made of a polypropylene composition having excellent heat-resistant rigidity. 2. 100 parts by weight of the propylene-based block copolymer composition (C) characterized in that it has a MFR (190 ° C .; 21.18 N) of 0.1 as a resin blend (D).
MF consisting of 20 to 0 parts by weight of one or more olefin polymers selected from the following groups (D1) to (D2):
R (230 ° C; 21.18N) 0.1 to 4g / 10min flexibility is used for olefin resin composition (E) for duct or hose-shaped flexible structure or bellows structure, high rigidity part (A) A tubular hollow molded article obtained by a connected parison method comprising a polypropylene composition having excellent heat resistance and rigidity. D1: an ethylene crystalline polymer having an MFR (190 ° C .; 2
1.18N) 0.1-5g / 10min, density 0.910-0.930g /
An ethylene polymer having a cm ³ and a crystal melting point (Tm) of 100 to 115 ° C. D2: ethylene-vinyl acetate copolymer with MFR
(190 ° C; 21.18N) 0.1-5g / 10min, density 0.920
0.935 g / cm ³ , crystal melting point (Tm) 90-108 ° C., vinyl acetate content 1-10% by weight. 3. A flexible structure or bellows structure obtained by a blow molding method comprising the propylene-based block copolymer composition (C) or the olefin-based resin composition (E) according to claim 1 or 2. Air ducts, air hoses and joint parts having flexibility and functionality as a cylindrical hollow molded article. [0001]