JPH09104789A - Propylene polymer composition and foamed article thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polypropylene resin composition which has an excellent property especially for recycling because of its slight decrease in melt tension on re-melting in addition to its high melt tension, superior rigidity, impact resistance and moldability. SOLUTION: This polypropylene resin composition consists of 100 pts.wt. resin made up of (A) a treated resin article which is a polypropylene resin having properties of (a) and (b) described below and treated by an ionizing radiation and (B) a polypropylene resin with a (B) component content of 0-90wt.% and 0.01-2 pts.wt. oxide of a metal belonging to group II of the periodic table. (a) melt flow rate: not more than 10g/10min. (b) ratio of isotactic pentad: not less than 0.965.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene resin composition having a high melt tension and a foam thereof. More specifically, a polypropylene resin composition having high melt tension, good rigidity, impact resistance and moldability, and a slight decrease in melt tension after remelting, and particularly excellent recyclability The present invention relates to a foam obtained by foam molding.

[0002]

2. Description of the Related Art Polypropylene is generally inexpensive,
It is widely used as an industrial material for automobile parts, electric / electronic parts, and various packaging materials by taking advantage of its properties such as light weight, chemical resistance, acid resistance, and heat resistance. 2. Description of the Related Art In recent years, there has been a strong demand for improving the properties of polypropylene-based materials as products have higher functionality or cost competition. However, since polypropylene resins generally have low melt tension, they have the drawback of being inferior in moldability such as extrusion molding, laminate molding, blow molding, and foam molding. As a method for solving this problem, for example, a method of reacting an organic peroxide and a crosslinking assistant in a molten state (Japanese Patent Laid-Open No. 59-93711).
JP-A-61-252754, etc.), a method of reacting a low decomposition temperature peroxide in an inert atmosphere (JP-A-2-2).
98536), a method of irradiating with an electron beam in an inert atmosphere to perform heat treatment (JP-A-62-121704), or a method in which an alkoxysilane compound and a foaming agent (and a crosslinking auxiliary agent) are blended with polypropylene. A molded product obtained by irradiating the molded product with ionizing radiation and then heat-foaming it (Japanese Patent Laid-Open No. Hei 3
221542 and Japanese Patent Laid-Open No. 4-63844) have been proposed.

[0003]

However, although the former three methods among the above all improve some of the characteristics, the melt tension is still insufficient, and they are melted when remelted for recycling. It has a drawback that the tension is extremely lowered. In addition, the method using an organic peroxide has a problem that odor remains. Further, both of the latter foaming methods have a problem that the melt tension is lowered when the foaming is carried out by heating, and skill is required for the foaming operation. Further, when a cross-linking agent is used, there are problems in controllability of cross-linking degree and recyclability for reuse. The present invention has been made in view of the above circumstances, and has a high melt tension, and a decrease in melt tension during recycling is small, and a polypropylene resin composition having good mechanical strength such as rigidity and a foam thereof. The purpose is to provide.

[0004]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have achieved the above-mentioned object by combining an ionizing radiation-treated product of a specific polypropylene resin with an oxide of a Group II metal of the periodic table. Based on this finding, the present invention has been completed.

That is, the present invention comprises (A) a resin-treated product obtained by treating a polypropylene resin having the following properties (a) and (b) with ionizing radiation and (B) a polypropylene resin. 100 parts by weight of a resin component having a composition ratio of 0 to 90% by weight and (C) Periodic Table II
Provided is a polypropylene resin composition comprising 0.01 to 2 parts by weight of a group metal oxide. (A) Melt flow rate: 10 g / 10 minutes or less (b) Isotactic pentad fraction: 0.965 or more

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The resin-treated product (A) in the present invention is a polypropylene-based resin described below, which has the following properties and is treated with ionizing radiation. (A) Melt flow rate: 10 g / 10 minutes or less (b) Isotactic pentad fraction: 0.965 or more The MFR of the polypropylene resin is preferably 8 g / 10 minutes or less, and particularly preferably 7 g / 10 minutes or less. It is suitable. MF
When R exceeds 10 g / 10 minutes, the melt tension decreases. Further, the isotactic pentad fraction (hereinafter referred to as “IP”) means an isotactic fraction in a pentad unit in a polypropylene molecular chain, preferably 0.968 or more, and more preferably 0.970 or more. is there. IP is 0.96
When it is less than 5, rigidity and melt tension are lowered, which is not preferable. In addition, for the measurement of IP, a nuclear magnetic resonance apparatus ( ¹³ C-NMR) using isotope carbon is used, and the method is, for example, A. Zambelli; Macromolecules, 6 , 925 (1973), the same, 8 , 5
87 (1975), ibid, 13 , 267 (1980).

As a polypropylene resin satisfying the above, for example, a solid catalyst containing a magnesium compound, a titanium compound, a halogen-containing compound and an electron-donating compound as essential components can be used, and further, a general formula: TiXa.Yb (in the formula, X Represents a halogen atom of Cl, Br, I, a represents 3 or 4, and b represents an integer of 3 or less) and polypropylene obtained by polymerization using an improved catalyst.

The ionizing radiation irradiation treatment can be carried out by subjecting the propylene-based resin powder or pellets to high vacuum in an inert gas or air atmosphere. Examples of the ionizing radiation include X-rays, α rays, γ rays and electron beams,
Gamma rays and electron rays are particularly preferable. The irradiation dose is generally 5 to 200 kGy, preferably 10 to 150
kGy, especially 15-100 kGy, is preferred. The treated product may be further heat-treated under a vacuum or an inert gas atmosphere at 80 to 130 ° C. for 10 minutes to 2 hours. The melt tension of the resin-treated product (A) obtained by the irradiation treatment is preferably 5 g or more, and particularly preferably 6 g or more. The MFR is preferably 0.1 to 20 g / 10 minutes, and particularly preferably 0.15 to 15 g / 10 minutes.

The polypropylene resin (B) in the present invention is a homopolymer of propylene or propylene and other α-olefin of 20% by weight or less, such as ethylene, butene-1,4-methylpentene-1, Examples thereof include block or random copolymers with octene-1 and the like. These resins may be used alone or in combination of two or more. Melt flow rate of component (B) (JI
According to SK7210, measured at 230 ° C. and a load of 2.16 kg, hereinafter referred to as “MFR”) is usually 0.05 to 50.
It is 0 g / 10 minutes, preferably 0.1 to 300 g / 10 minutes, and particularly preferably 0.2 to 200 g / 10 minutes.

In the present invention, the component (B) is mainly added in consideration of cost and is not an essential component. The ratio of the component (B) in the resin component is at most 90% by weight, preferably 85% by weight or less, and particularly preferably 80% by weight or less. If the content of component (B) exceeds 90% by weight, not only foaming becomes difficult, but also open cells are likely to occur, which is not preferable.

The (C) Group II metal oxide used in the present invention (hereinafter referred to as "metal oxide") is
Examples thereof include zinc oxide, cadmium oxide, magnesium oxide, calcium oxide and barium oxide. Among these, zinc oxide and magnesium oxide are preferable. The metal oxide used in the present invention may be a commercially available product as it is, but preferably has a purity of 93.0% by weight or more. The amount of the metal oxide compounded is 0.01 to 2 parts by weight, preferably 0.015 to 1.8 parts by weight, particularly preferably 0.015 to 1.8 parts by weight, based on 100 parts by weight of the resin component comprising the components (A) and (B). 0.02 to 1.5 parts by weight is preferred. The blending amount is 0.
If the amount is less than 01 parts by weight, the melt tension at the time of remelting is significantly reduced. On the other hand, if it exceeds 2 parts by weight, coloring or odor is caused, which is not preferable. The MFR of the obtained composition is usually 0.1 to 20 g / 10 minutes, and 0.5 to 10 g / 1.
0 is preferred.

Further, in the resin composition of the present invention, a nucleating agent having an effect of growing a crystal by becoming a crystal nucleus by being added to a crystalline resin such as polypropylene in the synthetic resin field may be added. . Examples of the nucleating agent include metal salts of carboxylic acids, dibenzylidene sorbitol derivatives,
There are inorganic compounds such as alkali metal salts and talc.
Specific examples include sodium benzoate, aluminum adipate, aluminum-pt-butylbenzoate, 1,3,2,4-dibenzylidene sorbitol,
1,3,2,4-bis (p-methylbenzylidene) sorbitol, 1,3,2,4-bis (p-ethylbenzylidene) sorbitol, 1,3-p-chlorobenzylidene-2,4-p-methyl Benzylidene sorbitol, sodium-bis (4-t-butylphenyl) phosphate, sodium-bis (4-t-methylphenyl) phosphate, potassium-bis (4,6-di-t-butylphenyl) phosphate, sodium -2-2'-methylene-bis (4,6-di-t-butylphenyl) phosphate, sodium-2-2'-ethylidene-bis (4
6-di-t-butylphenyl) phosphate, talc, calcium carbonate and the like. High density polyethylene can also be used as a nucleating agent.

The blending ratio of the nucleating agent is generally 0.05 to 20 parts by weight with respect to 100 parts by weight of the resin content, and there is a preferable ratio depending on the kind. In the case of an organic system excluding inorganic compounds, it is usually 0.05 to 1.0% by weight, and 0.08 to
0.8 wt% is preferable, and 0.1 to 0.5 wt% is particularly preferable. On the other hand, in the case of an inorganic compound such as talc and high density polyethylene, it is usually 1 to 20% by weight, preferably 2 to 18% by weight, particularly 5 to 15% by weight. When an inorganic compound is used, it may be treated with a titanate-based, silane-based, aluminum-based coupling agent, a surface treatment agent such as a fatty acid, a fatty acid metal salt, or a fatty acid ester.

The resin composition of the present invention can be obtained by a conventionally known mixing method of the above components. For example, a method of mixing using a Henschel mixer, a ribbon mixer, and the like, and then performing melt mixing using a kneading device such as a mixing roll, a Banbury mixer, a kneader, and an extruder can be used. The temperature for melt mixing is generally 170 to 28.
It is 0 degreeC, and it is preferable to carry out in the range of 180-260 degreeC. Further, the resin composition of the present invention, if desired, various conventional additives such as antioxidants, weather resistance stabilizers, antistatic agents, lubricants, antifogging agents, electrical property improvers, processability improvers,
A pigment, a softening agent, etc. may be added within a range that does not impair the object of the present invention.

Examples of the foaming agent (D) in the present invention include inorganic foaming agents, volatile foaming agents, decomposable foaming agents and the like. Examples of the volatile blowing agent include aliphatic hydrocarbons such as propane, butane, pentane, isobutane, neopentane, isopentane, hexane and heptane; cycloaliphatic hydrocarbons such as cyclobutane and cyclopentane; methyl chloride, methylene chloride and dichloro. Fluoromethane, chlorotrifluoromethane, dichlorodifluoromethane, chlorodifluoromethane, difluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, monochloropentafluoroethane, 1,1,
1,2-tetrafluoroethane, 1-chloro-1,1-
Examples thereof include halogenated hydrocarbons such as difluoroethane, 1,2-dichloro-2,2,2-trifluoroethane and 1,1-dichloro-1-fluoroethane. Examples of the decomposable blowing agent include azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, sodium carbonate, sodium bicarbonate, potassium bicarbonate, and the like. These foaming agents can be used as a mixture of two or more kinds. The blending amount of the foaming agent in the present invention varies depending on the type of the foaming agent and the desired expansion ratio, but is generally 0.1 to 30 with respect to 100 parts by weight of the total composition of the components (A) to (C). Parts by weight, preferably 0.2 to 20 parts by weight.

Further, at the time of foaming, talc, fine calcium silicate, aluminum stearate, as a cell regulator,
A small amount of inorganic powder such as calcium carbonate, barium sulfate or silica; an acidic salt of polyvalent carboxylic acid; a reaction product of polyvalent carboxylic acid and sodium carbonate or sodium bicarbonate may be added. Further, as a foam shrinkage inhibitor, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, N-methylstearic acid amide, N-ethylstearic acid amide, N, N-distearic acid amide, dilauric acid amide, distearic acid Higher aliphatic amides such as acid amides and dipalmitic acid amides;
Dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosylamine, decosylamine, N-methyloctadecylamine, N-ethyloctadecylamine, hexadecylpropyleneamine,
Saturated higher alkyl amines such as octadecyl propylene amine may be added.

The foam of the present invention can be obtained by a known foaming method using the above components. For example, there are a so-called gas foam molding method and extrusion foam molding method in which a foaming agent is added, melt-kneaded under pressure, and extruded into the atmosphere, or a heat foaming method in which a molded product is heated to foam, whichever method is used. You may use. The obtained foam has the advantages of excellent heat resistance and mechanical strength, a high expansion ratio, a uniform cell diameter, and a large number of closed cells.

[0018]

The present invention will be described in more detail with reference to the following examples. The physical properties were measured by the following methods. (1) IP measurement conditions Measuring instrument: JNM-GSX400 manufactured by JEOL Ltd. Measurement mode: Proton decoupling method Pulse width: 8.0 μsec Pulse repetition time: 5.0 sec Accumulation frequency: 20000 times Solvent: 1, 2, 4, -Trichlorobenzene / heavy benzene mixed solvent (75/25% by volume) Internal circulation: Hexamethyldisiloxane Sample concentration: 300 mg / 3.0 ml Solvent measurement temperature: 120 ° C (2) Table 1 and conditions according to MFR JIS K7210. It was measured at 14. (3) Melt tension Using a melt tension tester type 2 manufactured by Toyo Seiki Seisaku-sho, a nozzle (caliber: 2.095 m;
m, L / D = 3.8), a strand extruded into the air at 23 ° C. at a speed of 15 mm / min, and a take-up speed of 6.4 m.
It is expressed by the load (g) applied at the time of taking it up at m / min. (4) Apparent density Based on JIS K6767. (5) Appearance The foamed sheet was evaluated by visual observation in the following three stages. ○ ・ ・ ・ ・ Roughness and open cell parts are almost absent △ ・ ・ ・ ・ Roughness and open cell parts are a little × ・ ・ ・ ・ Roughness and open cell parts are considerable (6) Elongation at break Compliant with JIS K6767A method .

The propylene resin for component (A) has an MFR of 0.09 g / 10 minutes and an IP of 0.9.
92 homopolypropylene (hereinafter referred to as "PP-A"), MFR is 0.58 g / 10 min, and IP is 0.
Homopolypropylene having 978 (hereinafter referred to as "PP-B") and MFR having 2.2 g / 10 min and IP of 0.992 (hereinafter referred to as "PP-B").
C ”) was used. 16g MFR for comparison
Homopolypropylene having an IP of 0.994 (hereinafter referred to as "PP-D") and an MFR of 2.
A homopolypropylene having an IP of 0.943 at 3 g / 10 minutes was used (hereinafter referred to as "PP-E").
2.4 g of MFR as the propylene resin as the component (B)
Homo polypropylene of 10 minutes (hereinafter "PP-1"
Homopolypropylene having an MFR of 7.8 g / 10 minutes (hereinafter referred to as "PP-2") and a propylene random copolymer having an MFR of 3.2 g / 10 minutes and an ethylene content of 1.2% by weight ( Hereinafter referred to as "PP-3").

Zinc oxide (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.1% by weight, hereinafter referred to as "C-
1 ”) and magnesium oxide (manufactured by the same company, purity 9)
8.2% by weight, hereinafter referred to as "C-2") was used.
(D) Component 1 with chlorodifluoromethane as a foaming agent
A mixture of 40:60 (by weight) chloro-1,1-difluoroethane (hereinafter referred to as “GAS”) and a mixture of 50:50 (by weight) sodium bicarbonate and citric acid (hereinafter referred to as “NAH”). Using.

Preparation Example of Component (A) (XPP-1 to 3, X
PP-A, B) Propylene resin (granular) shown in Table 1 below as the (A) component is a γ-ray irradiation device (manufactured by Koga Isotope).
Alternatively, an electron beam irradiation device (manufactured by Nisshin High Voltage Co., Ltd.) was used to irradiate the irradiation dose shown in Table 1 under a nitrogen atmosphere. Then, after heat-treating at 130 ° C. for 1 hour in a nitrogen atmosphere, M
FR was measured. Table 1 shows the results.

[0022]

[Table 1]

Examples 1-10, Comparative Examples 1-7 Component (A) whose type and amount are shown in Table 2,
As the component (B) and the component (C) and the stabilizer, di-
0.05 parts by weight of t-butyl-p-cresol, pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-butylhydroxyphenyl) propionate]
0.1 parts by weight and 0.1 parts by weight of calcium stearate are used as a super mixer (Kawata Seisakusho, SMV20 type).
After mixing using a twin-screw extruder (Nakaya Seisakusho, AS
30 type) was kneaded at a temperature of 230 ° C. to form pellets. MFR and melt tension M for these pellets
T ₁ (1 pass) was measured. Further, each pellet was melt-mixed again using the melt-kneading device and pelletization was repeated twice, and then the melt tension MT ₃ (3 passes) was measured. Table 2 shows the above results.

[0024]

[Table 2]

Examples 11 to 15 and Comparative Examples 8 to 10 100 parts by weight of the component compositions (A) to (C) shown in Table 3 were used at a temperature of 220 using a tandem extruder consisting of a 50 mmφ extruder and a 65 mmφ extruder. The mixture was kneaded at 0 ° C., the component (D) was press-fitted in the middle of the extruder, and extruded from the T die having a lip width of 600 mm and a gap of 0.4 mm into the atmosphere at a die temperature of 160 ° C. to obtain a foamed sheet. The physical properties of the obtained foamed sheet were measured. Further, the foamed sheet and the burr were used as raw materials to remold the foamed sheet in the same manner as above. The physical properties of the obtained regenerated foamed sheet were measured in the same manner. Table 3 shows the above results.

Examples 16 and 17, Comparative Example 11 100 parts by weight of the component compositions (A) to (C) shown in Table 3 were mixed with 2 parts by weight of a foaming agent (NAH) and dry blended with a tumbler. Melt extrusion foaming was performed with an extruder to produce a foamed sheet. The same measurement as in the above example was performed on the obtained foamed sheet. Table 3 shows the results.

[0027]

[Table 3]

[0028]

INDUSTRIAL APPLICABILITY The resin composition of the present invention has a high melt tension, good rigidity, impact resistance and moldability, and a slight decrease in melt tension due to remelting. It's excellent and its foam is used in vehicles, ships,
It is useful in various fields such as interior materials for buildings and packaging materials for electric and precision equipment.

Claims (4)

[Claims] 1. A resin-treated product obtained by subjecting (A) a polypropylene resin having the following properties (a) and (b) to ionizing radiation treatment and (B) a polypropylene resin:
Resin component in which the composition ratio of the component (B) is 0 to 90% by weight
A polypropylene resin composition comprising 100 parts by weight and (C) 0.01 to 2 parts by weight of an oxide of a Group II metal of the periodic table. (A) Melt flow rate: 10 g / 10 minutes or less (b) Isotactic pentad fraction: 0.965 or more 2. The polypropylene resin composition according to claim 1, wherein the resin-treated product (A) has the following properties (i) and (ii). (I) Melt flow rate: 0.1 to 20 g / 10 minutes (ii) Melt tension at a temperature of 230 ° C .: 5 g or more 3. The polypropylene resin composition according to claim 1, wherein the ionizing radiation is γ ray or electron beam. 4. The polypropylene-based resin composition according to claim 1, wherein (D) a foaming agent is added to the polypropylene resin composition.
Polypropylene resin foam obtained by blending 30 parts by weight.