JPH10316808A - Polypropylene composition for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition useful for producing household electric appliances for cooking, etc., by compounding specific polyethylene, a phenolic antioxidizing agent, a specific phosphorus stabilizer, and a sulfur- based heat stabilizer. SOLUTION: This composition comprises 100 pts.wt. of polypropylene having a melt flow rate of 1-100 g/10 min, 0.005-1 pt.wt. of a phenolic antioxidizing agent [preferably a phenol compound of formula I or formula II (R<1> , R<2> are each methyl; R<3> , R<4> are each a 1-3C alkylene)], 0.01-1 pt.wt. of a phosphorus stabilizer [e.g. 2,2',2"-nitrilotriethyl-tris(3,3,5,5'-tetra-t-butyl-1,1'-biphenyl-2,2' -diyl) phosphite], 0.005-1 pt.wt. of a sulfur-based heat stabilizer, and, if necessary, 0.005-1 pt.wt. of hydrotalcite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to heat resistance (heat aging resistance, heat discoloration resistance) or steam resistance (steam aging resistance, steam resistance, etc.) particularly used for cooking home appliances such as rice cookers and jar pots. (Discoloration property).

[0002]

BACKGROUND OF THE INVENTION Polypropylene (PP) having excellent heat resistance (heat aging resistance) is widely used for cooking home appliances such as rice cookers and jar pots.

[0003] These cooking home appliances are required not to be discolored, especially yellowed or deteriorated even when exposed to heat or steam. The causes of such discoloration and deterioration are directly caused by heat and steam, but are caused by pigments and resin additives, and parts attached to polypropylene molded products constituting cooking home appliances, such as rubber packing materials. And have not been identified. Regardless of the cause of discoloration deterioration, a method of blending various antioxidants with polypropylene has been conventionally used as a measure for preventing discoloration deterioration.

Heretofore, it has been common practice to combine phenolic antioxidants, sulfur-based heat stabilizers and phosphorus-based stabilizers with polypropylene. In this case, as the amount of the phenolic antioxidant increases, the heat resistance improves, but the heat discoloration deteriorates. Also,
If the amount of the phenolic antioxidant is reduced and the amount of the phosphorus stabilizer is increased in order to improve the heat discoloration resistance, heat resistance and mold corrosion resistance (used during the production of molded products) Resistance to corrosion of the mold).

[0005] In recent years, as the use environment conditions of cooking home appliances have become increasingly severe, further improvement against discoloration and deterioration has been demanded, and improvement in mold corrosion resistance has also been demanded.

Therefore, the inventors of the present invention have proposed that tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl)] is added to polypropylene as a phenolic antioxidant.
Propionate] methane and 1,3,5-trimethyl-2,4,6
-Tris (3,5-di-t-butyl-4-hydroxyphenyl)
Benzylbenzene, distearyl-3,3'-thiodipropionate as a sulfur-based heat stabilizer, and tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylenediene as a phosphorus-based stabilizer By blending with phosnite, a polypropylene composition having excellent heat resistance was obtained.

However, a polypropylene composition for obtaining an injection-molded article excellent in mold corrosion resistance and heat discoloration resistance has been sought. The inventors of the present application have further studied diligently. (1) Polypropylene (PP) has a phenolic antioxidant and a specific phosphorus antioxidant (2,2 ', 2 "-nitrilotriethyl-tris [3, 3 ', 5,5'-tetra-t-butyl
-1,1'-biphenyl-2,2'-zyl] phosphite) and a sulfur-based heat stabilizer in a specific ratio are excellent in mold corrosion resistance, and are resistant to heat from this composition. (2) In the polypropylene composition, as a phenolic antioxidant, 3,9-bis ｛2-
[3- (3-t-butyl-4-hydroxy-5-methylphenyl)
Propionyloxy] -1,1-dimethylethyl-2,4,8,1
When combined with 0-tetraoxaspiro [5.5] undecane and 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxyphenyl) benzylbenzene, heat resistance And further improved steam resistance and steam resistance,
The present invention has been completed.

[0008]

An object of the present invention is to provide an injection molded article having an excellent balance of heat aging resistance and heat discoloration resistance, particularly an injection molded article having an excellent balance of heat aging resistance, heat discoloration resistance, steam aging resistance and steam discoloration resistance. Body can be molded, and
It is an object of the present invention to provide a polypropylene composition having excellent mold corrosion resistance so that corrosion of a mold used during production of a molded article can be suppressed.

[0009]

The polypropylene composition for injection molding according to the present invention has a melt flow rate (ASTM D 1238, 230 ° C,
100 parts by weight of polypropylene (PP) having a load of 2.16 kg) of 1 to 100 g / 10 minutes, 0.005 to 1 part by weight of a phenolic antioxidant (A), and a phosphorus-based stabilizer (B)
0.01 to 1 part by weight, and sulfur-based heat stabilizer (C) 0.1.
005 to 1 part by weight, and the phosphorus-based stabilizer (B) has the following general formula [I]

[0010]

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2,2 ', 2 "-nitrilotriethyl represented by
-It is characterized by being tris [3,3 ', 5,5'-tetra-t-butyl-1,1'-biphenyl-2,2'-zyl] phosphite. In addition to the polypropylene (PP), the phenolic antioxidant (A), the phosphorus-based stabilizer (B) and the sulfur-based heat-resistant stabilizer (C),
Hydrotalcites (D) are converted to polypropylene (P
P) It is preferable to contain 0.005 to 1 part by weight based on 100 parts by weight.

The phenolic antioxidant (A) includes the following general formula [II]

[0013]

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[Wherein R ¹ and R ² represent a methyl group or t-
A butyl group, at least one of which is a t-butyl group, and R ³ and R ⁴ each independently represent a group having 1 to 3 carbon atoms.
A phenolic compound represented by the following general formula [III]:

[0015]

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[Wherein R ¹ and R ² represent a methyl group or t-
A butyl group, at least one of which is a t-butyl group, and R ³ and R ⁴ each independently represent a group having 1 to 3 carbon atoms.
At least one phenolic antioxidant (A
1) is preferable.

In particular, the phenolic antioxidant (A)
As one or more phenolic antioxidants (A1) selected from the phenolic compound represented by the general formula [II] and the phenolic compound represented by the general formula [III], and the following general formula [IV]

[0018]

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[Wherein R ¹ and R ² represent a methyl group or t-
A butyl group, at least one of which is a t-butyl group]
And a phenol compound represented by the following general formula [V]

[0020]

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[Wherein R ⁵ , R ⁶ and R ⁷ are represented by the following formulas:

[0022]

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(Wherein R ¹ and R ² represent a methyl group or t-
A butyl group, at least one of which is a t-butyl group)
At least one phenolic antioxidant (A
2) and a phenolic antioxidant (A)
The total content is 0.005 to 1 part by weight based on 100 parts by weight of polypropylene (PP), and the weight ratio of the phenolic antioxidants (A1) to (A2) [(A1) / (A2) ]
Is preferably 1/7 to 7/1.

The phenolic compound represented by the general formula [II] includes tetrakis [methylene-3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate] methane is preferred.

The phenol compound represented by the general formula [III] includes 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy]-
1,1-dimethylethyl {-2,4,8,10-tetraoxaspiro [5.5] undecane is preferred.

Examples of the phenol compound represented by the general formula [IV] include 1,3,5-trimethyl-2,4,6-tris (3,3
5-Di-t-butyl-4-hydroxyphenyl) benzylbenzene is preferred.

As the phenol compound represented by the general formula [V], tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate is preferable. As the sulfur-based heat stabilizer (C), the following general formula [VI]

[0028]

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Wherein R ⁸ is independently an alkyl group having 12 to 18 carbon atoms, and R ⁹ is each independently an alkylene group having 1 to 3 carbon atoms. Sulfur compounds are preferred. In particular, dimyristil
-3,3'-thiodipropionate, dilauryl-3,3'-thiodipropionate, dipalmityl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate are preferred.

[0030]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the polypropylene composition for injection molding according to the present invention will be described in detail.

The polypropylene composition for injection molding according to the present invention comprises a polypropylene (PP), a phenolic antioxidant (A), a phosphorus-based stabilizer (B), a sulfur-based heat-resistant stabilizer (C), and if necessary. And additives such as hydrotalcites (D).

Polypropylene (PP) The polypropylene (PP) used in the present invention is usually
Any polypropylene may be used as long as it is used for injection molding, and a propylene homopolymer,
Either a random copolymer with ethylene or a block copolymer with ethylene can be used. These polypropylenes (PP) may be filled with a filler such as talc.

The polypropylene (P) used in the present invention
P) melt flow rate (MFR; ASTM D 1238,230)
° C, load 2.16 kg) is 1 to 100 g / 10 min, preferably 3 to 50 g / 10 min, and more preferably 4 to 40 g / min.
10 minutes. When a polypropylene (PP) having a melt flow rate within the above range is used, a polypropylene composition having excellent injection moldability can be obtained.

Phenolic antioxidant (A) The phenolic antioxidant (A) used in the present invention includes a phenolic compound represented by the following general formula [II] and a phenolic compound represented by the following general formula [III] Compounds are preferred. In particular, the phenol compound represented by the general formula [III] is more preferable from the viewpoint of heat discoloration resistance and vapor discoloration resistance.

These phenol compounds may be used alone or in combination of two or more. In the present invention, in particular, one or more phenolic antioxidants (A1) selected from a phenolic compound represented by the general formula [II] and a phenolic compound represented by the general formula [III], It is preferable to use together with one or more phenolic antioxidants (A2) selected from the phenol compound represented by the formula [IV] and the phenol compound represented by the following general formula [V].

When the phenol compound represented by the general formula [IV] is compared with the phenol compound represented by the general formula [V], the phenol compound represented by the general formula [IV] is more preferable in view of steam aging resistance. The phenol compound represented by the general formula [V] is more preferable from the viewpoint of heat discoloration resistance and vapor discoloration resistance.

The total content of the phenolic antioxidant (A) in the polypropylene composition according to the present invention is 0.00 to 100 parts by weight of the polypropylene (PP).
5 to 1 part by weight, preferably 0.01 to 0.70 part by weight,
More preferably, it is 0.05 to 0.50 parts by weight. When the phenolic antioxidants (A1) and (A2) are used in combination, the phenolic antioxidants (A1) and (A2)
Weight ratio [(A1) / (A2)] is 1/7 to 7/1, preferably 1/6 to 6/1, and more preferably 1/5 to 5/1.

The following general formula [II]

[0039]

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In the formula, R ¹ and R ² represent a methyl group or
a t-butyl group, at least one of which is a t-butyl group. R ³ and R ⁴ are each independently an alkylene group having 1 to 3 carbon atoms, for example, a methylene group, an ethylene group or a propylene group.

The phenolic compound represented by the general formula [II] includes, for example,
(1) R ¹ and R ² are t-butyl groups, and R ³ and R
^A phenol compound wherein ⁴ is a methylene group; (2) a phenol compound wherein R ¹ and R ² are t-butyl groups and R ³ and R ⁴ are ethylene groups; and (3) a phenol compound wherein R ¹ and R ² are t-butyl. A phenolic compound wherein R ³ and R ⁴ are propylene groups, (4) R ¹ is a methyl group, and R ² is t-
A phenolic compound wherein R ³ and R ⁴ are methylene groups, (5) R ¹ is a methyl group, and R ² is t-
A phenolic compound wherein R ³ and R ⁴ are ethylene groups, (6) R ¹ is a methyl group, and R ² is t-
A phenolic compound wherein R ³ and R ⁴ are propylene groups, (7) R ¹ is a methyl group, and R ² is
a phenol compound wherein R ³ is a methylene group and R ⁴ is an ethylene group; (8) R ¹ is a methyl group, R ² is a t-butyl group, and R ³ is a methylene group; A phenolic compound wherein R ⁴ is a propylene group;
(9) R ¹ is a methyl group, R ² is a t-butyl group,
A phenol compound in which R ³ is an ethylene group and R ⁴ is a methylene group, (10) R ¹ is a methyl group, and R ² is t-
A phenol compound in which R ³ is an ethylene group, R ⁴ is a propylene group, (11) R ¹ is a methyl group, R ² is a t-butyl group, and R ³ is a propylene group. A phenol compound wherein R ⁴ is a methylene group, (1
2) R ¹ is a methyl group; R ² is a t-butyl group;
^A phenol compound wherein ³ is a propylene group and R ⁴ is an ethylene group; (13) a phenol compound wherein R ¹ and R ² are t-butyl groups, R ³ is a methylene group and R ⁴ is an ethylene group , (14) a phenol compound in which R ¹ and R ² are t-butyl groups, R ³ is a methylene group and R ⁴ is a propylene group, (15) R ¹ and R ² are t-butyl groups. , A phenol compound wherein R ³ is an ethylene group and R ⁴ is a methylene group, (16) R ¹ and R ² are a t-butyl group, R ³ is an ethylene group, and R ⁴ is a propylene group. Phenol compound, (17) R ¹ and R ² are t-
A phenol compound wherein R ³ is a propylene group and R ⁴ is a methylene group; (18) R ¹ and R ²
Is a t-butyl group, R ³ is a propylene group, R ⁴
And a phenol compound having an ethylene group. Among them, the phenol compound of the above (15), that is, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane is preferable.

The following general formula [III]

[0043]

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In the formula, R ¹ and R ² represent a methyl group or
a t-butyl group, at least one of which is a t-butyl group. R ³ and R ⁴ are each independently an alkylene group having 1 to 3 carbon atoms, for example, a methylene group, an ethylene group or a propylene group.

The phenolic compound represented by the general formula [III] includes, for example,
(1) a phenol compound in which R ¹ and R ² are t-butyl groups and R ³ and R ⁴ are methylene groups; (2) a phenol compound in which R ¹ and R ² are
a phenol compound in which R ³ and R ⁴ are ethylene groups, a phenol compound in which R ¹ and R ² are t-butyl groups, and R ³ and R ⁴ are propylene groups, 4) R ¹ is a methyl group, R ² is a t-butyl group, R ³ and R ⁴ are methylene groups, (5) R ¹ is a methyl group, R ² is t-butyl A phenol compound wherein R ³ and R ⁴ are ethylene groups, (6) a phenol compound wherein R ¹ is a methyl group, R ² is a t-butyl group, and R ³ and R ⁴ are a propylene group , (7) a phenol compound in which R ¹ is a methyl group, R ² is a t-butyl group, R ³ is a methylene group, and R ⁴ is an ethylene group; (8) R ¹ is a methyl group , R
² is a t-butyl group, R ³ is a methylene group, R ⁴
Is a phenolic compound, (9) a phenolic compound in which R ¹ is a methyl group, R ² is a t-butyl group, R ³ is an ethylene group, and R ⁴ is a methylene group; (10) R ¹ is a methyl group, R ² is t- butyl, R ³ is ethylene group, a phenolic compound R ⁴ is a propylene group, (11) R ¹ is a methyl group, R ²
Is a t-butyl group, R ³ is a propylene group, R ⁴
Is a methylene group, (12) a phenol compound in which R ¹ is a methyl group, R ² is a t-butyl group, R ³ is a propylene group, and R ⁴ is an ethylene group, (13) A phenol compound in which R ¹ and R ² are t-butyl groups, R ³ is a methylene group, and R ⁴ is an ethylene group; (14) R ¹ and R ² are t-butyl groups, and R ³ is A phenolic compound wherein m is a methylene group and R ⁴ is a propylene group, (15) a phenolic compound wherein R ¹ and R ² are t-butyl groups, R ³ is an ethylene group and R ⁴ is a methylene group; 16) a phenol compound in which R ¹ and R ² are t-butyl groups, R ³ is an ethylene group, and R ⁴ is a propylene group; (17) R ¹ and R ² are t-butyl groups; ³ is a propylene group, a phenolic compound R ⁴ is a methylene ^{group, (18) R 1, R} 2 is a t- butyl group, R ³ is Pro Phenol compounds which are a pyrene group and R ⁴ is an ethylene group. Among them, the phenol compound of the above (5), that is, 3,9-bis {2- [3- (3-t-butyl-4
-Hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl {-2,4,8,10-tetraoxaspiro [5.5] undecane is preferred.

The following general formula [IV]

[0047]

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In the formula, R ¹ and R ² represent a methyl group or
a t-butyl group, at least one of which is a t-butyl group. Examples of the phenol compound represented by the general formula [IV] include, for example, (1)
A phenol compound wherein R ¹ and R ² are t-butyl groups, (2)
Examples include phenol compounds in which R ¹ is a methyl group and R ² is a t-butyl group. Among them, the phenol compound of the above (1), that is, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxyphenyl) benzylbenzene is preferable.

The following general formula [V]

[0050]

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In the formula, R ⁵ , R ⁶ and R ⁷ are groups represented by the following formulas.

[0052]

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In the formula, R ¹ and R ² are a methyl group or a t-butyl group, and at least one of them is a t-butyl group. Examples of the phenol compound represented by the general formula [V] include, in the general formula [V], (1) a phenol compound in which R ¹ and R ² are t-butyl groups, and (2) a phenol compound in which R ¹ is a methyl group. And a phenol compound in which R ² is a t-butyl group. Among them, the phenol compound of the above (1), that is, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate is preferable.

Phosphorus Stabilizer (B) Phosphorus stabilizer (B) used in the present invention is 2,2 ′, 2 ″ -nitrilotriethyl-tris [3,3 ′] represented by the following general formula [I]. , 5,5'-Tetra-t-butyl-1,1'-biphenyl-2,
2'-Jill] phosphite.

[0055]

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The phosphorus-based stabilizer (B) is used in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the polypropylene (PP).
Preferably it is used in a proportion of 0.03 to 0.50 parts by weight, more preferably 0.05 to 0.30 parts by weight. When the phosphorus-based stabilizer (B) is used in the above ratio, a molded article having excellent heat aging resistance and heat discoloration resistance, and further having excellent heat aging resistance, steam aging resistance, heat discoloration resistance and steam discoloration resistance are formed. A polypropylene composition is obtained which allows the body to be injection molded.

Sulfur-based heat stabilizer (C) The sulfur-based heat stabilizer (C) used in the present invention is represented by the following general formula [VI].

[0058]

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R ⁸ in the general formula [VI] is independently an alkyl group having 12 to 18 carbon atoms, specifically, dodecyl, tridecyl, tetradecyl,
Examples include a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group.

R ⁹ is independently an alkylene group having 1 to 3 carbon atoms, for example, a methylene group, an ethylene group or a propylene group. Examples of the sulfur-based heat stabilizer represented by the general formula [VI] include (1) (C
_{12 H 25 -OOC-CH 2 -} ) 2 -S, (2) (C 12 H 25 -
_{OOC-C 2 H 4 -)} 2 -S, (3) (C 12 H 25 -OOC
—C ₃ H ₆ —) ₂ —S, (4) (C ₁₃ H ₂₇ —OOC—CH _{2
-) 2 -S, (5)} (C 13 H 27 -OOC-C 2 H 4 -) 2 -
_{S, (6) (C 13} H 27 -OOC-C 3 H 6 -) 2 -S,
_{(7) (C 14 H 29} -OOC-CH 2 -) 2 -S, (8) (C
_{14 H 29 -OOC-C 2 H} 4 -) 2 -S, (9) (C 14 H 29
—OOC—C ₃ H ₆ —) ₂ —S, (10) (C ₁₅ H ₃₁ —OO
_{C-CH 2 -) 2 -S} , (11) (C 15 H 31 -OOC-C 2
_{H 4 -) 2 -S, (} 12) (C 15 H 31 -OOC-C 3 H 6 -)
_{2 -S, (13) (C} 16 H 33 -OOC-CH 2 -) 2 -S
_{, (14) (C 16 H} 33 -OOC-C 2 H 4 -) 2 -S, (15)
_{(C 16 H 33 -OOC-C} 3 H 6 -) 2 -S, (16) (C 17
_{H 35 -OOC-CH 2 -)} 2 -S, (17) (C 17 H 35 -O
_{OC-C 2 H 4 -)} 2 -S, (18) (C 17 H 35 -OOC-
_{C 3 H 6 -) 2 -S} , (19) (C 18 H 37 -OOC-CH
_{2 -) 2 -S, (20} ) (C 18 H 37 -OOC-C 2 H 4 -) 2
—S, (21) (C ₁₈ H ₃₇ —OOC—C ₃ H ₆ —) ₂ —S and the like. Among them, (2), (5), (8), (11), (1
The sulfur compounds (4), (17) and (20) are preferred. In particular, (2)
Dilauryl-3,3'-thiodipropionate, (8) dimyristyl-3,3'-thiodipropionate, (14) dipalmityl-3,3'-thiodipropionate, (20) Stearyl
-3,3'-thiodipropionate is preferably used.

In the present invention, the sulfur-based heat stabilizer (C) is used in an amount of 0.005 to 1 part by weight, preferably 0.02 to 0.1 part by weight, per 100 parts by weight of the polypropylene (PP).
70 parts by weight, more preferably 0.05 to 0.50 parts by weight. When the sulfur-based heat stabilizer (C) is used in the above ratio, the heat resistance (heat aging resistance and heat discoloration resistance) and the steam resistance (steam aging resistance and steam discoloration resistance) can be further improved. .

Hydrotalcites (D) The hydrotalcites (D) used as required in the present invention are double salt compounds represented by the following formula, and may be natural products or synthetic compounds. It may be an article.

(M ²⁺ ) _1-x Al _x (OH) ₂ (A ⁿ⁻ ) _{2 / n} · mH ₂ O wherein x is a value satisfying the relationship 0 <x ≦ 0.5. There, m is a real number, M ²⁺ is, Mg, a Ca or Zn, a ^n-is the n-valent anion. ] In the present invention, in particular M ²⁺ is Mg ^2+, synthetic products A ^n- is CO ₃ is ² is preferable.

The hydrotalcites (D) can be used alone or in combination of two or more. The hydrotalcites (D) are 0.005 to 1 part by weight, preferably 0.01 to 0.50 part by weight, more preferably 0.02 to 0.20 part by weight based on 100 parts by weight of the polypropylene (PP). Used in parts by weight.
When the hydrotalcites (D) are used in the above ratio, the heat discoloration resistance, the steam discoloration resistance, and the mold corrosion resistance are further improved.

Other Ingredients In the polypropylene composition for injection molding according to the present invention, polypropylene (PP), phenolic antioxidant (A), phosphorus stabilizer (B), sulfur-based heat stabilizer (C) and In addition to the hydrotalcites (D), conventionally known additives for polypropylene, such as fillers such as talc and glass fiber, and pigments, can be blended within a range that does not impair the object of the present invention. The total amount of such additives is usually 40 parts by weight or less based on 100 parts by weight of polypropylene (PP), but may be larger.

Polypropylene Composition The polypropylene composition for injection molding according to the present invention comprises the above-mentioned polypropylene (PP), phenolic antioxidant (A), phosphorus-based stabilizer (B), and sulfur-based heat-resistant stabilizer (C). , And if necessary, hydrotalcites (D) and the like are contained in the above-described specific ratio.

Among the polypropylene compositions for injection molding according to the present invention, the following compositions are preferred. (1) Polypropylene (PP), a phenol compound represented by the general formula [III], a phenol compound represented by the general formula [IV] or [V], a phosphorus-based stabilizer (B), A polypropylene composition comprising a sulfur compound represented by the formula [VI].

Among such compositions, particularly preferred examples of the polypropylene composition include the polypropylene compositions in Examples 4 and 6 described below. (2) Polypropylene (PP), a phenol compound represented by the general formula [III], a phenol compound represented by the general formula [IV], a phosphorus-based stabilizer (B), and a compound represented by the general formula [VI] A polypropylene composition comprising a sulfur compound represented by the formula and hydrotalcites.

Among such compositions, a particularly preferred example of the polypropylene composition is described in Example 5 below.
And the like. The polypropylene composition for injection molding according to the present invention can be prepared by melt-kneading the above components using a kneader such as a single-screw or twin-screw extruder.

[0070]

Industrial Applicability The polypropylene composition for injection molding according to the present invention is an injection-molded article having an excellent balance between heat aging resistance and heat discoloration resistance, particularly heat aging resistance, heat discoloration resistance, steam aging resistance and steam discoloration resistance. It is possible to mold an injection-molded article having an excellent balance of properties, and it is excellent in mold corrosion resistance so that corrosion of a mold used in manufacturing the molded article can be suppressed.

[0071]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The polypropylene, phenol-based antioxidant, phosphorus-based stabilizer, sulfur-based heat stabilizer and hydrotalcite used in the examples and comparative examples are as follows. Polypropylene PP-1 · Propylene homopolymer Density (ASTM D 1505): 0.91 g / cm ³ MFR (ASTM D 1238, 230 ° C, load 2.16 kg): 10 g /
10 minutes Phenolic antioxidant (1) A1-1. Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane [Ciba Geigy Co., Ltd., trade name Irganox (Irgano)
x) 1010] (2) A1-2.3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl}- 2,4,8,10-Tetraoxaspiro [5.5] undecane [Adeka stub AO- manufactured by Asahi Denka Kogyo Co., Ltd.
80] (3) A2-1 • 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl
-4-hydroxyphenyl) benzylbenzene [Ciba Geigy Co., Ltd., trade name Irganox (Irgano
x) 1330] (4) A2-2 • tris (3,5-di-t-butyl-4-hydroxybenzyl)
Isocyanurate [Ciba Geigy Co., Ltd., product name Irganox (Irgano
x) 3114] Phosphorus stabilizer (1) P-1 Phosphorus stabilizer (B) (= 2,2 ', 2 "-nitrilotriethyl
-Tris [3,3 ', 5,5'-tetra-t-butyl-1,1'-biphenyl-2,2'-diyl] phosphite [Ciba Geigy Co., Ltd., trade name Irgafos
s) 12] (2) P-2 Tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylene-diphosphonite [Sandstab P
-EPQ] (3) P-3 Tris (2,4-di-t-butylphenyl) phosphite [Ciba Geigy Co., Ltd., trade name Irgafos
s) 168] sulfur-based heat stabilizer S-1-3,3'-thiodipropionate [Yoshitomi Pharmaceutical Co., Ltd., trade name DMTP] hydrotalcite-hydrotalcite (Mg ₄ Al ₂ ( OH) ₁₂ CO ₃
3H ₂ O) [Kyowa Chemical Industry Co., Ltd., trade name TH4A]

[0073]

EXAMPLES 1-6 AND COMPARATIVE EXAMPLES 1-5 Each component was melt-kneaded at 190 ° C. using a single-screw extruder according to the recipe shown in Table 1.
A polypropylene composition was prepared.

Next, each of the polypropylene compositions was injection-molded using an injection molding machine to obtain JIS No. 1 specimen and a square plate having a thickness of 3 mm. The square plate was further cut using a microtome to obtain a film having a thickness of 60 μm.

The obtained JIS No. 1 specimen and film were subjected to the following high-temperature storage test, high-temperature and high-humidity test, steam resistance test, and rust test. (1) High temperature storage test (discoloration due to heat) After leaving JIS No. Specimen at 150 ° C. for 336 hours in a gear oven, a color difference meter [Nippon Denshoku Industries Co., Ltd.
, NDHＮ80] was used to measure the color difference (ΔE). (2) High-temperature and high-humidity test (discoloration due to steam (steam)) JIS No. 1 specimen was set about 1 cm above the water surface in a closed container filled with water to a position about 50 mm from the bottom, and the container was sealed. At 120 ° C. for 168 hours. After that, remove the specimen from the sealed container,
The color difference (ΔE) was measured using the same color difference meter as described above. (3) Heat Aging Test (Surface Deterioration due to Hot Air) The heat aging test was conducted by placing a JIS-1 test piece in a gear oven in which the furnace was maintained at 160 ° C.
A sheet was used, and the resistance to surface deterioration due to heat was evaluated based on the average time until a certain surface crazing occurred. (4) Steam aging resistance test (surface deterioration by steam (steam)) A film (size: thickness: 60 μm, length: 60 mm, width: 3 mm) was put in a steam heater keeping the inside of the furnace at 153 ° C., and steam was applied to the film surface. And air were blown, and the time until the film was cut was measured. Since there was variation in the time until the film was cut, the number of samples was set to 10 each, and the average time for cutting was used to evaluate the resistance to surface deterioration due to steam. The spraying is performed at a supply air flow rate of 100
This was performed under the condition of liter / min. (5) Rust test (corrosion resistance to mold) As shown in FIG. 1, a sample (polypropylene composition) 3 and a test piece 4 were placed in a petri dish 2 covered with an aluminum foil 1.
(A mild steel plate (SPCC-SB 240; size 0.5 mm × 40 mm × 50 mm, perforated with 0.3 mmφ) not subjected to rust prevention treatment) was set, and wrapped with aluminum foil 1.

The petri dish 2 is placed in a constant temperature dryer (not shown) set at 280 ° C., and the thermocouple 5 is inserted into the aluminum foil package, and the temperature of the sample is set at 250 ± 5 ° C.
When the pressure rose, oxygen (air) was purged with nitrogen gas.

After the purging, the temperature of the sample is again set to 250 ±
When the temperature reaches 5 ° C., the temperature is kept within the range for 10 ± 0.5 minutes, and then the petri dish is taken out of the constant temperature drier, and while the polypropylene composition is soft, the polypropylene composition is mixed with the aluminum foil. Was cut to the size of a mild steel plate with scissors, and allowed to cool at room temperature for about 1 hour.

After cooling, the test piece was taken out, attached to a suspension stand, and placed in a desiccator containing distilled water kept at 60 ° C. for 15 ± 10 hours.
0.5 hours, to promote rusting. Thereafter, the test piece was taken out from the desiccator, and the degree of rusting of the test piece was determined by comparison with a rusting standard plate.

The degree of rusting was evaluated from 1 to 8 points, and the most rusted test piece was set to "1", and the rusting-free test piece was set to "8". Table 1 shows the results.

[0080]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a rusting test (corrosion resistance to a mold) performed in Examples and Comparative Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Aluminum foil 2 ... Petri dish 3 ... Sample (polypropylene composition) 4 ... Test piece (mild steel plate) 5 ... Thermocouple

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 5/524 C08K 5/524 // B29K 23:00

Claims (10)

[Claims] (1) A melt flow rate (ASTM D 1238, 230)
100 parts by weight of polypropylene (PP) having a load of 1.16 g / 10 min at 100 ° C., a phenolic antioxidant (A) of 0.005 to 1 part by weight, and a phosphorus-based stabilizer (B) 0.1. A composition comprising 0.01 to 1 part by weight and 0.005 to 1 part by weight of a sulfur-based heat stabilizer (C). The phosphorus-based stabilizer (B) has the following general formula [I]: Formula 1 2,2 ', 2 "-nitrilotriethyl-tris [3,
3 ', 5,5'-Tetra-t-butyl-1,1'-biphenyl-2,2'-diyl] phosphite. 2. In addition to the polypropylene (PP), the phenolic antioxidant (A), the phosphorus stabilizer (B) and the sulfur-based heat stabilizer (C), a hydrotalcite (D) 2. The polypropylene composition for injection molding according to claim 1, wherein the polypropylene composition is contained in an amount of 0.005 to 1 part by weight based on 100 parts by weight of (PP). 3. The phenolic antioxidant (A) is represented by the following general formula [II]: [Wherein, R ¹ and R ² are a methyl group or a t-butyl group, at least one of which is a t-butyl group, and R ³ and R ⁴ are each independently a group having 1 to 3 carbon atoms. A phenolic compound represented by the following general formula [III]: [Wherein, R ¹ and R ² are a methyl group or a t-butyl group, at least one of which is a t-butyl group, and R ³ and R ⁴ are each independently a group having 1 to 3 carbon atoms. A phenolic antioxidant (A1) selected from phenolic compounds represented by the following formula (1): 4. The phenolic antioxidant (A) is one or more phenolic antioxidants selected from the phenolic compounds represented by the general formula [II] and the phenolic compounds represented by the general formula [III]. (A1) and the following general formula [IV] Wherein R ¹ and R ² are a methyl group or a t-butyl group, at least one of which is a t-butyl group; and a phenol compound represented by the following general formula [V]: [Wherein R ⁵ , R ⁶ and R ⁷ are represented by the following formula: (Wherein R ¹ and R ² are a methyl group or a t-butyl group, at least one of which is a t-butyl group). Phenolic antioxidant (A2), and the total content of phenolic antioxidant (A) is 0.005 to 1 with respect to 100 parts by weight of polypropylene (PP).
2 parts by weight, and the weight ratio [(A1) / (A2)] between the phenolic antioxidants (A1) and (A2) is 1/7 to 7/1. 4. The polypropylene composition for injection molding according to any one of 3. 5. The phenol compound represented by the general formula [II] is tetrakis [methylene-3- (3,5-di-t-butyl)
5. The polypropylene composition for injection molding according to claim 3, wherein the composition is -4-hydroxyphenyl) propionate] methane. 6. The phenol compound represented by the general formula [III] is 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1 5. The polypropylene composition for injection molding according to claim 3, which is 1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] undecane. 7. The phenolic compound represented by the general formula [IV] is 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-
5. The polypropylene composition for injection molding according to claim 4, wherein the composition is (butyl-4-hydroxyphenyl) benzylbenzene. 8. The method according to claim 4, wherein the phenol compound represented by the general formula [V] is tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate. A polypropylene composition for injection molding. 9. The sulfur-based heat stabilizer (C) is represented by the following general formula [VI]: [Wherein, R ⁸ is each independently 12 to 1 carbon atoms.
8 is an alkyl group, and R ⁹ is each independently an alkylene group having 1 to 3 carbon atoms.] The polypropylene composition for injection molding according to claim 1, Stuff. 10. The sulfur compound represented by the general formula [VI] is dimyristyl-3,3'-thiodipropionate, dilauryl-3,3'-thiodipropionate, dipalmityl-
The polypropylene composition for injection molding according to claim 9, which is 3,3'-thiodipropionate or distearyl-3,3'-thiodipropionate.