JP2000178390A - Polypropylene composition for blow holding and molded item made thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polypropylene composition which gives a blow molded item having a high stiffness and an excellent parting strength by compounding at least either a propylene homopolymer or a propylene block copolymer with an amorphous inorganic filler. SOLUTION: This composition is prepared by compounding 100 pts.wt. polypropylene comprising at least either a propylene hompolymer having a melt flow rate of 0.1-1 g/10 min and an extinction quotient (A997/A993) of 0.90 or higher or a propylene block copolymer having a melt flow rate of 0.1-1 g/10 min and an ethylene content of 3-15 wt.% with 5-30 pts.wt. amorphous inorganic filler (e.g. calcium carbonate) having a particle size of 0.05-100 μm. The block copolymer comprises propylene homopolymer blocks and 5-20 wt.% propylene-ethylene random copolymer blocks having an ethylene content of 40-80 wt.% and a melt flow rate of 0.001-0.1 g/10 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition for blow molding particularly suitable for blow molding and a molded product thereof. More specifically, the present invention relates to a blow-molded polypropylene resin composition comprising a specific polypropylene resin and an amorphous inorganic filler, which is capable of obtaining a blow-molded product having high rigidity and excellent parting strength, and a molded product thereof.

[0002]

2. Description of the Related Art Blow-molded articles using polypropylene resin are used for small containers for daily necessities.
In recent years, application to large industrial parts such as bumpers and spoilers of automobiles has been studied. In the use of such large industrial parts, high rigidity is often required as a characteristic of the raw material. As a technique for improving the rigidity of a blow-molded polypropylene resin composition, JP-A-4-120145 discloses a technique in which talc is blended with a polypropylene resin. Although this technique improves the rigidity, it has the problem that the strength of the part where the parison has been cut off by the blow mold, the so-called parting part, is weak. Raw materials for molding are desired.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a polypropylene resin composition which is particularly suitable for blow molding to obtain a blow molded article having high rigidity and excellent parting strength, and a molded article using the same. The purpose is to:

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, it has been found that a composition obtained by blending a specific polypropylene resin with an amorphous inorganic filler has a high rigidity and a high particle density. The present inventors have found that a polypropylene composition for blow molding which is particularly suitable for blow molding, which can provide a molded article having excellent strength, has been completed based on this finding. That is, the present invention includes the following.

(1) A melt flow rate (MFR) of 0 to 100 parts by weight of at least one type of polypropylene selected from the following a) and b) is mixed with 5 to 30 parts by weight of an amorphous inorganic filler. A polypropylene composition for blow molding of 1 to 1.0 g / 10 minutes. a) MFR is 0.1 to 1 g / 10 min, IR-τ (absorbance ratio between 997 cm ^-1 and 973 cm ^-1 measured by infrared spectrophotometer (A ₉₉₇ / A ₉₇₃₎₎ of 0.90 or more propylene Homopolymer, b) polypropylene block copolymer having a total MFR of 0.1 to 1 g / 10 min consisting of a propylene homopolymer portion (referred to as a homo portion) and a propylene-ethylene random copolymer portion (referred to as a RC portion) Wherein the IR-τ in the homo part is 0.90 or more, the ethylene content in the polypropylene block copolymer (referred to as total ethylene) is 3 to 15% by weight, and the ethylene content in the RC part (RC
Ethylene) is 40 to 80% by weight, the proportion of the RC part to the whole block copolymer (RC segment) is 5 to 20% by weight, and the MFR of the RC part (RCFMR) is 0.001 to 0.1 g / 10 min. A certain polypropylene block copolymer.

(2) Consists of the following c) and d), wherein c)
And a melt flow rate (MFR) in which 5 to 30 parts by weight of an amorphous inorganic filler is blended with 100 parts by weight of polypropylene in which the mixing weight ratio of d) is c: d = 1: 5 to 5: 1. Is a polypropylene composition for blow molding of 0.1 to 1.0 g / 10 min. c) MFR of 0.1 to 1 g / 10 min, IR-τ of 0.9
2) or more propylene homopolymer, d) total MFR is 0.1 to 1 g / 10 min, IR-τ of homo part is 0.92 or more, and total ethylene is 3 to 15
% By weight, 40 to 80% by weight of RC ethylene, 5 to 20% by weight of RC segment, and 0.001 to 0.
1 g / 10 min polypropylene block copolymer.

(3) The blow molding polypropylene resin composition according to any one of the above (1) or (2), wherein the amorphous inorganic filler is calcium carbonate.

(4) A blow molded article using the polypropylene resin composition for blow molding according to any one of the above items (1) to (3).

[0009]

Propylene homopolymer used in [a preferred embodiment of the present invention, the crystallinity index represented by the absorbance ratio between 997 cm ^-1 and 973 cm ^-1 measured by infrared spectrophotometer (A ₉₉₇ / A ₉₇₃₎ (IR-τ) is 0.90 or more, preferably 0.92 or more. If the IR-τ is significantly lower than 0.90, the rigidity and heat resistance decrease. In addition, the MF
R is 0.1 from the viewpoint of melt extrudability and blow moldability.
The range is preferably 1 to 10 g / 10 minutes. If the MFR is lower than 0.1, extrusion molding of the molten resin becomes difficult, and MF
If R exceeds 1 g / 10 minutes, the draw-down property of the parison increases, and the blow moldability deteriorates.

[0010] One of the polypropylenes used in the present invention, a polypropylene block copolymer, has a homo part and an R
It is a polypropylene block copolymer having a total MFR of 0.1 to 1 g / 10 min. Total MFR, from the viewpoint of melt extrudability and blow moldability,
The range is preferably from 0.1 to 1 g / 10 minutes. The total M
If the FR is lower than 0.1 g / 10 minutes, extrusion molding of the molten resin is difficult. If the FR exceeds 1 g / 10 minutes, the draw-down property of the parison increases, and the blow moldability deteriorates.

The polypropylene block copolymer comprises:
IR-τ of homo part is 0.90 or more, preferably 0.92
That is all. When the IR-τ of the homo part is significantly lower than 0.90, rigidity and heat resistance are reduced.

The polypropylene block copolymer has an ethylene content (total ethylene) in the polypropylene block copolymer of 3 to 15% by weight.
If the total ethylene content is less than 3% by weight, the impact strength decreases,
If it is 15% by weight or more, the rigidity decreases.

The R of the polypropylene block copolymer
The ethylene content of part C (RC ethylene) is 40 to 80
% By weight, and the ratio of the RC part to the polypropylene block copolymer (RC segment) is 5 to 20% by weight.
It is. If the RC ethylene content is less than 40% by weight, the impact resistance is reduced, and if it is more than 80% by weight, the stiffness is reduced.
If the content of the C segment is less than 5% by weight, the impact strength is reduced,
If it is more than 20% by weight, the rigidity is reduced.

The MFR (RCMFR) of the RC portion of the polypropylene block copolymer used in the present invention is 0.0
01 to 0.1 g / 10 minutes, and the RCMFR is 0.0
When it is lower than 01 g / 10 minutes, the gloss is reduced and the appearance of the molded article is deteriorated. On the other hand, if it is larger than 0.1 g / 10 minutes, the impact strength is reduced.

As the polypropylene used in the present invention,
When a mixture of the above-mentioned propylene homopolymer and polypropylene block copolymer is used, a composition excellent in balance between rigidity, heat resistance and impact resistance can be obtained. The mixing ratio of the propylene homopolymer and the polypropylene block copolymer is preferably from 1: 5 to 5: 1.

The polypropylene used in the present invention is prepared by converting propylene or propylene with ethylene by a usual polymerization method such as a slurry polymerization method or a gas phase polymerization method using a coordination compound catalyst system such as a Ziegler-Natta catalyst. It can be obtained by polymerization. IR of homo part of propylene homopolymer and polypropylene block copolymer
−τ can be adjusted by adding an electron donor during the polymerization. The MFR can be adjusted by adjusting the amount of hydrogen added during polymerization. The polypropylene block copolymer can be obtained by polymerizing 80 to 95% by weight of a homo part, and then polymerizing 5 to 20% by weight of an RC part having an ethylene content of 40 to 80% by weight.

The amorphous inorganic filler used in the present invention is a fine powdered inorganic substance having no specific shape such as a plate or a needle. Examples of the amorphous inorganic filler include:
Examples thereof include calcium carbonate, barium sulfate, and magnesium carbonate. The particle size of the amorphous inorganic filler is 0.1.
It is 0.5-100 μm, preferably 0.1-50 μm. As such an amorphous inorganic filler, a commercially available inorganic filler may be used.

The polypropylene composition for blow molding of the present invention is prepared by adding 5 to 30 parts by weight of the amorphous inorganic filler to 100 parts by weight of the above-mentioned polypropylene. When the addition ratio of the amorphous inorganic filler is less than 5 parts by weight, rigidity and heat resistance are poor, and when it is more than 30 parts by weight,
Parting strength decreases and blow moldability also deteriorates.

The polypropylene composition for blow molding according to the present invention contains a nucleating agent, an antistatic agent, a light stabilizer, polyethylene, ethylene-propylene rubber, styrene butadiene rubber and the like as long as the effects of the present invention are not impaired. Can be added and used in combination.

The polypropylene composition for blow molding of the present invention can be prepared by mixing predetermined amounts of polypropylene, an amorphous inorganic filler and the above-mentioned various additives with a usual mixing apparatus, for example, a Hensel mixer (trade name), a spar mixer, a ribbon blender. Can be obtained by mixing using
Further, the mixture can be melt-kneaded at a temperature of 180 to 250 ° C. with a single-screw or twin-screw extruder, a Brabender, or the like, and granulated to obtain pellets.

A blow-molded article using the polypropylene composition for blow-molding of the present invention can be obtained by a usual direct blow molding method.
To the molding machine set in, melt extruded into a parison shape,
Pre-blowing is performed as necessary, and the parison is held in a blow molding die, and pressurized air (0.5 to 1 MPa) is blown into the parison from an air nozzle to inflate the parison, thereby pressing the parison against the inner wall of the die. A molding method in which air pressure is applied until the shape is fixed can be exemplified. Further, the composition of the present invention can also be used as a composition for an inner layer of a blow molded article having a multilayer structure.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited by these specific examples. The evaluation of the characteristics used in the following Examples and Comparative Examples was performed by the following methods.

(1) MFR: MFR was measured based on JIS K 7210 test condition 14 (230 ° C., 21.18 N). (Unit is g / 10min)

(2) Rigidity: As a measure of the rigidity of a molded product,
The flexural modulus of the composition was measured according to the test method of JIS K7203. (Unit is MPa)

(3) Heat resistance: As a measure of the heat resistance of the molded article, the heat distortion temperature of the composition was measured according to the method B of JIS K7207. (Unit is ° C)

(4) Impact strength: As a measure of the impact strength of a molded product, the Izod impact strength at 0 ° C. of the composition was measured in accordance with JIS K.
It was measured according to 7110. (Unit is KJ / m2)

(5) IR-τ: The sample was formed into a film by a press molding machine at 200 ° C. and immediately cooled by a press molding machine adjusted to 20 ° C. to obtain a film having a thickness of about 40 μm. Put the film into an annealing tube
Annealing was performed for 1 hour in an oil bath at 35 ° C. The film after annealing as a sample, the absorbance ratio between 997 cm ^-1 and 973 cm ^-1 using an infrared spectrophotometer (A
₉₉₇ / _A973 ) and IR-τ was determined. In the case of the polypropylene block copolymer, a sample was withdrawn during polymerization of the homo part, and IR-τ of the homo part was measured.

(6) Composition of polypropylene block copolymer I) Total MFR: Measured by the method of (1). II) MFR of homo part: Propylene homopolymer was extracted from the polymerization unit of the homo part and measured by the method of the above (1). III) Homo part IR-τ: Propylene homopolymer was extracted from the homo part polymerization vessel and measured by the method of (5) above.

IV) The total ethylene: polypropylene block copolymer was formed into a film by a press molding machine at 200 ° C. and immediately cooled by a press molding machine adjusted to 20 ° C. to obtain a film having a thickness of about 100 μm. The absorbance at 720 cm -1 of the film was measured using an infrared spectrophotometer, and the total ethylene was determined from a previously prepared calibration curve (unit:% by weight).

V) RC Ethylene: A polypropylene block copolymer is formed into a film by a press molding machine at 200 ° C., and immediately cooled by a press molding machine adjusted to 20 ° C. to form a film having a thickness of about 100 μm. 730 cm ^-1 and 720 cm of the film using an infrared spectrophotometer
The absorbance ratio of ^-1 ( _A730 / _A720 ) was measured, and RC ethylene was determined using a previously prepared calibration curve (unit: wt%).

VI) RC segment: Determined by the following formula using measured values of total ethylene and RC ethylene. RC segment = (total ethylene / RC ethylene)
× 100 (unit is% by weight).

VII) RCMFR: Determined by the following equation using the values of the total MFR, the MFR of the homologous part, and the RC segment. log (total MFR) = (1-RC segment) ×
log (homo part MFR) + RC segment × log (R
CMFR).

(7) Parting strength: using a direct blow molding machine, molding temperature 230 ° C., mold temperature 20 ° C.
A bottle having a volume of 600 ml was molded under the molding conditions described above. From the bottom of the bottle having a part, a plate-like test piece having a width of about 5.5 mm was prepared using a punching tooth such that the part was located at the center. The test piece was attached so that the part was located at the center between the chucks.
A tensile test was performed under the conditions of 5 mm and a tensile speed of 200 mm / min, and the maximum load and elongation were measured.

(8) Formability: using an accumulator-type blow molding machine at a molding temperature of 220 ° C. and a weight of 2.3 kg.
Was extruded to form a kerosene can having an inner volume of 18 liters, and the moldability was evaluated according to the following criteria. ：: No problem in moldability. X: The draw-down was large or punctured and could not be molded.

In the examples and comparative examples, the following polypropylenes and inorganic fillers were used.・ PP: Total MFR 0.3 g / 10 min, IR-τ 0.93 of homo part, total ethylene 8.0 wt
%, RC ethylene 60wt%, RC segment 13.3
wt%, RCMFR 0.03g / 10min polypropylene block copolymer

.PP: MFR 0.3 g / 10 min,
Polypropylene homopolymer with IR-τ0.93 ・ PP: Total MFR 0.3 g / 10 min, IR-τ0.91 in homo part, total ethylene 8.0 wt
%, RC ethylene 60wt%, RC segment 13.3
wt%, RCMFR 0.03 g / 10 min polypropylene block copolymer PP: MFR 1.5 g / 10 min, IR-τ0.
94 polypropylene homopolymer

-Charcoal: calcium carbonate, average particle size 1.7μ-Sulfur burr: barium sulfate, average particle size 0.5μ-Talc: average particle size 2.5μ-Mica: average particle size 13μ-Wallast: wallast Knight, average particle size 6.5

Example 1 MFR 0.3 g / 10 min, IR-τ of the homo part was 0.
93, 8% by weight of total ethylene, 60% by weight of RC ethylene, 13.3% by weight of RC segment, RCCMFR 0.
To 100 parts by weight of a 03 g / 10 min polypropylene block copolymer, 5 parts by weight of calcium carbonate and [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane as a stabilizer were added in an amount of 0%. 0.15 parts by weight of calcium stearate and 0.15 parts by weight of Henschel mixer (trade name)
After that, the mixture was granulated at a temperature of 250 ° C. using a 65 mm uniaxial granulator to obtain pellets. Using these pellets, a molding temperature of 230 with a direct blow molding machine
A bottle having a capacity of 600 ml was molded under the molding conditions of 20 ° C. and a mold temperature of 20 ° C. to prepare a test piece having parting characteristics, and the parting strength was measured. Further, using an accumulative blow molding machine, at a molding temperature of 220 ° C., a weight of 2.3 k
g of parison, extruding an 18 liter kerosene can,
The moldability was evaluated. Further, the MFR, flexural modulus, heat deformation temperature, and Izod impact strength of the pellet were measured.
The results are shown in Table 1 below.

Examples 2 to 10 and Comparative Examples 1 to 6 Preparation of pellets and test pieces having parting properties according to Example 1 using the raw materials described in Table 1 below,
The parting strength was measured and an 18 liter kerosene can was molded, and its moldability was evaluated. The pellet M
FR, flexural modulus, heat distortion temperature, and Izod impact strength were measured. The results are shown in Table 1 below.

[0040]

[Table 1]

As shown in Table 1, the polypropylene composition for blow molding of the present invention is excellent in rigidity, heat resistance and impact resistance, and has high breaking strength and elongation at the parting portion of the blow molded product. Is higher.

[0042]

EFFECT OF THE INVENTION By using the composition of the present invention, a blow-molded article having excellent rigidity, heat resistance and impact resistance and excellent parting strength can be obtained. It is suitable.

Claims (4)

[Claims] At least one selected from the following a) and b):
A blow molding polypropylene composition comprising 100 parts by weight of a kind of polypropylene and 5 to 30 parts by weight of an amorphous inorganic filler and having a melt flow rate (MFR) of 0.1 to 1.0 g / 10 minutes. a) MFR is 0.1 to 1 g / 10 min, IR-τ (absorbance ratio between 997 cm ^-1 and 973 cm ^-1 measured by infrared spectrophotometer (A ₉₉₇ / A ₉₇₃₎₎ of 0.90 or more propylene Homopolymer, b) polypropylene block copolymer having a total MFR of 0.1 to 1 g / 10 min consisting of a propylene homopolymer portion (referred to as a homo portion) and a propylene-ethylene random copolymer portion (referred to as a RC portion) Wherein the IR-τ in the homo part is 0.90 or more, the ethylene content in the polypropylene block copolymer (referred to as total ethylene) is 3 to 15% by weight, and the ethylene content in the RC part (RC
Ethylene) is 40 to 80% by weight, the proportion of the RC part to the whole block copolymer (RC segment) is 5 to 20% by weight, and the MFR of the RC part (RCFMR) is 0.001 to 0.1 g / 10 min. A certain polypropylene block copolymer. 2. An amorphous form comprising 100 parts by weight of polypropylene having the following c) and d), wherein the mixing weight ratio of c) and d) is c: d = 1: 5 to 5: 1. A melt flow rate (M) containing 5 to 30 parts by weight of an inorganic filler.
FR) of 0.1 to 1.0 g / 10 min. c) MFR of 0.1 to 1 g / 10 min, IR-τ of 0.9
2) or more propylene homopolymer, d) total MFR is 0.1 to 1 g / 10 min, IR-τ of homo part is 0.92 or more, and total ethylene is 3 to 15
% By weight, 40 to 80% by weight of RC ethylene, 5 to 20% by weight of RC segment, and 0.001 to 0.
1 g / 10 min polypropylene block copolymer. 3. The blow molding polypropylene resin composition according to claim 1, wherein the amorphous inorganic filler is calcium carbonate. 4. A blow-molded article using the polypropylene resin composition for blow molding according to claim 1.