JPH06220260A - Stabilized polyolefin composition - Google Patents

Abstract

PURPOSE:To provide the subject compsn. givig a molded article which has a greatly improved resistance to long-term thermal oxidation and is long used in contact with a heating medium in a heat exchange system. CONSTITUTION:The objective compsn. is prepd. by compounding 100 pts.wt. polyolefin with 0..05-5 pts.wt. condensate of 4,4'-thiobisphenol with an aliph. aldehyde and 0.05-5 pts.wt. at least one thioether compd. selected from the group consisting of a dialkyl disulfide, 2,4-bis(octylthio)-6-(4-hydroxy-3,5-di-t- butylanilino)-1,3,5-triazine, and 2,4-bis[(octylthio)methyl]-o-cresol.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to stabilized polyolefin compositions. More specifically, the present invention relates to a stabilized polyolefin composition capable of obtaining a molded article having excellent stability for long-term contact use with a heating medium used in a heat exchange system.

[0002]

2. Description of the Related Art Generally, polyolefin is relatively inexpensive and has excellent mechanical properties, and therefore it is used for producing various molded products such as injection molded products, hollow molded products, films, sheets and fibers. However, polyolefins, especially propylene-based polymers, are susceptible to thermal oxidative deterioration during molding and practical use because they have tertiary carbon which is susceptible to oxidation in the polymers. Therefore, various antioxidants have been widely used for the purpose of preventing such thermal oxidative deterioration. However, when a polyolefin composition formed by blending various antioxidants is molded, and the obtained molded product is used for an application such as a heat exchange system in which a heating medium such as an organic solvent is in long-term contact, the composition is Since the compounded antioxidant is extracted by the heating medium, there arises a problem that the long-term contact with the heating medium significantly deteriorates the thermal oxidation deterioration resistance (hereinafter, referred to as long-term thermal stability).

Therefore, for the purpose of improving the long-term thermal stability of polyolefin compositions, it has been widely practiced to use various phenol antioxidants and thioether antioxidants in combination with the polyolefin. Further, JP-A-53-16745 discloses that a plastic material has a molecular weight of 1,000 to 4,000 in order to stabilize the plastic against oxidation.
4,4'-thio-bis- (dialkylphenol) -formaldehyde condensate is added as an antioxidant to stabilize the plastic against oxidation. In this publication, the condensate alone is used as an antioxidant. It is described that not only can it be used, but it can also be used in combination with other antiaging agents.

[0004]

However, in order to solve the problem of long-term thermal stability, a conventionally known polyolefin composition obtained by combining polyolefin with various phenol-based antioxidants and thioether-based antioxidants has been proposed. Although there is a considerable improvement in long-term thermal stability, it is still not sufficiently satisfactory. In addition, the above-mentioned JP-A-53
The method for stabilizing plastics proposed in Japanese Patent No. 16745 has little improvement in long-term thermal stability, and in this publication, dialkyldisulfide as another antiaging agent,
2,4-bis (octylthio) -6- (4-hydroxy-3,5-di-t
There is no mention or suggestion that it can be used in combination with -butylanilino) -1,3,5-triazine or 2,4-bis [(octylthio) methyl] -o-cresol.

The present inventor has conducted earnest studies to obtain a composition which solves the above-mentioned problems relating to the polyolefin composition, that is, a polyolefin composition having improved long-term thermal stability. As a result, the molecular weight of polyolefin is 1,000 to 4,000.
4,4'-thio-bisphenol-aliphatic aldehyde condensate of the above and a composition comprising a specific thioether compound are respectively blended in a specific amount, it was found that it is possible to solve the drawbacks of the above polyolefin composition, this finding The present invention has been completed based on the above. As is clear from the above description, it is an object of the present invention to provide a stabilized polyolefin composition which can be used in a heat exchange system to obtain a molded article having excellent long-term thermal stability.

[0006]

The present invention has the following constitution. Molecular weight 1,000 per 100 parts by weight of polyolefin
To 4,000 4,4'-thio-bisphenol-aliphatic aldehyde condensate (hereinafter referred to as compound A) and one or more thioether compounds (hereinafter referred to as compound B) selected from the following: A stabilized polyolefin composition containing 0.05 to 5 parts by weight. Dialkyl disulfide 2,4-bis (octylthio) -6- (4-hydroxy-3,5-di
-t-Butylanilino) -1,3,5-triazine 2,4-bis [(octylthio) methyl] -o-cresol

The polyolefin used in the present invention is a crystalline homopolymer of α-olefin such as ethylene, propylene, butene-1, pentene-1, 4-methyl-pentene-1, hexene-1, octene-1, and the like. Polyolefin such as crystalline, low crystalline or amorphous random copolymer or crystalline block copolymer of two or more α-olefins, amorphous ethylene-propylene-nonconjugated diene terpolymer, etc. A copolymer of α-olefin with vinyl acetate or acrylic acid ester, a saponified product of the copolymer, a copolymer of these α-olefin and an unsaturated silane compound, an α-olefin and an unsaturated carboxylic acid or A copolymer of the anhydride, a reaction product of the copolymer and a metal ion compound, and a modification of the above-mentioned polyolefin with an unsaturated carboxylic acid or a derivative thereof. Examples of the polyolefin include olefin-modified polyolefins and silane-modified polyolefins obtained by modifying the above-mentioned polyolefins with unsaturated silane compounds. These polyolefins can be used alone or in combination of two or more kinds.

In addition to the above-mentioned polyolefins, various synthetic rubbers (for example, polybutadiene, polyisoprene, polychloroprene, chlorinated polyethylene, chlorinated polypropylene, fluororubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, styrene-butadiene- rubber).
Styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-
Styrene block copolymer, styrene-propylene-butylene-styrene block copolymer, etc.) or thermoplastic synthetic resin (eg polystyrene, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, polyamide, polyethylene terephthalate, poly polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyvinyl chloride, chlorinated polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, fluorine resin, petroleum resin (e.g. C ₅ petroleum resins, hydrogenated C ₅ system Petroleum resin, C
_9- based petroleum resin, hydrogenated C _9- based petroleum resin, C ₅ -C ₉ copolymerized petroleum resin, hydrogenated C ₅ -C ₉ copolymerized petroleum resin, acid-modified C _9- based petroleum resin, etc., DCPD resin (eg cyclo Pentadiene petroleum resin, hydrogenated cyclopentadiene petroleum resin, cyclopentadiene-C ₅ copolymer petroleum resin, hydrogenated cyclopentadiene-C ₅ copolymer petroleum resin, cyclopentadiene-C ₉ copolymer petroleum resin, hydrogenated cyclopentadiene- C ₉ copolymerized petroleum resin, cyclopentadiene-C ₅ -C ₉ copolymerized petroleum resin, hydrogenated cyclopentadiene-C ₅ -C ₉ copolymerized petroleum resin, etc., having a softening point of 80 to 200 ° C. Can also be used. Crystalline propylene homopolymer, a crystalline propylene copolymer containing 70% by weight or more of a propylene component, crystalline ethylene-propylene random copolymer, crystalline ethylene-propylene block copolymer,
Crystalline propylene-butene-1 random copolymer, crystalline ethylene-propylene-butene-1 terpolymer, crystalline propylene-hexene-butene-1 terpolymer and a mixture of two or more thereof. Particularly preferably used.

The compound A used in the present invention is 4,4 ′
-Thio-bis (2-methylphenol), 4,4'-thio-bis (2,5-dimethylphenol), 4,4'-thio-bis (2-methyl-6-t-butylphenol), 4, 4'-thio-bis (2-t-butyl-5-methylphenol), 4,4'-thio-bis (2-t-butyl-5-isopropylphenol), 4,4'-thio-bis (2 , 5-di-t-butylphenol), 4,4'-thio-bis (2-
Isopropyl-5-methylphenol), 4,4'-thio-bis (2-isoamyl-5-isopropylphenol), etc.
An example is a condensate of 4'-thio-bisphenol with an aliphatic aldehyde such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, having a molecular weight of 1,000 to 4,000, and particularly 4,4'-thio-bis (2 -t-Butyl-5-methylphenol) -formaldehyde condensate is preferred.

When the molecular weight of the compound A is less than 1,000,
Since the compound A is easily extracted from the polyolefin composition by the heating medium, the effect of improving the long-term thermal stability of the polyolefin composition is not sufficiently exerted, and the molecular weight is
When it exceeds 4,000, the above-mentioned extraction problem is solved, but the migration property of the compound A in the polyolefin composition is lowered, so that the antioxidant effect of the compound A is not sufficiently exhibited. Further, these compounds A may be used alone or in combination of two or more kinds. The compounding ratio of the compound A is 0.05 to 5 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the polyolefin.
When the amount is less than 0.05 parts by weight, the long-term thermal stability improving effect of the polyolefin composition is not sufficiently exerted, and when it is more than 5 parts by weight, further long-term thermal stability improving effect can be expected. Not only impractical but also uneconomical.

The compound B used in the present invention includes dinonyl disulfide, dilauryl disulfide, dimyristyl disulfide, dipalmityl disulfide, distearyl disulfide, dibehenyl disulfide, 2,4-bis (octylthio) -6- (4 Examples thereof include -hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine and 2,4-bis [(octylthio) methyl] -o-cresol. Especially distearyl disulfide, 2,4-bis (octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine and 2,4-bis [(octylthio) methyl ] -O-Cresol is preferred. These compounds B may be used alone or in combination of two or more kinds. The compounding ratio of the compound B is 0.05 to 5 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the polyolefin. When the amount is less than 0.05 parts by weight, the long-term thermal stability improving effect of the polyolefin composition is not sufficiently exerted, and when it is more than 5 parts by weight, further long-term thermal stability improving effect can be expected. Not only impractical but also uneconomical.

In the composition of the present invention, various additives which are usually added to polyolefins such as phenol type (excluding compound A), thioether type (excluding compound B) and phosphorus type are added. Antioxidant such as, light stabilizer, heavy metal deactivator (copper damage inhibitor), clarifier,
Nucleating agents, lubricants, antistatic agents, anti-fog agents, anti-blocking agents, anti-drop agents, radical generators such as peroxides, flame retardants, flame retardant aids, pigments, halogen scavengers, metal soaps, etc. Dispersant or neutralizer, organic or inorganic antibacterial agent,
Inorganic fillers (eg talc, mica, clay, wollastonite, zeolite, kaolin, bentonite, perlite, diatomaceous earth, asbestos, calcium carbonate,
Aluminum hydroxide, magnesium hydroxide, silicon dioxide, titanium dioxide, zinc oxide, magnesium oxide, zinc sulfide, barium sulfate, calcium silicate, aluminum silicate, glass fiber, potassium titanate, carbon fiber, carbon black, graphite and metal Fiber etc.),
Coupling agent (for example, silane, titanate, boron, aluminate, zircoaluminate, etc.)
The above-mentioned inorganic filler or organic filler (for example, wood flour, pulp, waste paper, synthetic fiber, natural fiber, etc.) which has been surface-treated with a surface-treating agent such as the above can be used in combination within the range not impairing the object of the present invention. .

In the composition of the present invention, a predetermined amount of each of the above-mentioned compound A and compound B and the above-mentioned various additives usually added to polyolefin is added to a polyolefin by a conventional mixing device such as a Henschel mixer (trade name), a super mixer, Mix using a ribbon blender, Banbury mixer, etc., and melt kneading temperature 150 ℃ ～ 3 with a normal single screw extruder, twin screw extruder, Brabender or roll.
It can be obtained by melt-kneading and pelletizing at 20 ° C, preferably 180 ° C to 290 ° C. The obtained composition is used for producing a desired molded article by various molding methods such as an injection molding method, an extrusion molding method and a blow molding method.

In the present invention, the heat exchange system mainly means a heat source portion for heating or cooling, pipes connecting them,
The heating medium circulates in the pipes. Further, as the heating medium used in the heat exchange system, water, ethylene glycol, polyethylene glycol,
Examples thereof include propylene glycol, polypropylene glycol, glycerin, silicone oil, vegetable oil, polybutene, mineral oil, alkylbenzene, alkylnaphthalene, dichlorobenzene, diphenyl oxide, and a mixture of two or more thereof.

[0015]

In the present invention, the compound A acts as a radical chain inhibitor, and the compound B acts as a peroxide decomposing agent synergistically with the antioxidant action of the compound A, thereby significantly improving long-term thermal stability. It is thought that it is doing.

[0016]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The evaluation methods used in Examples and Comparative Examples were as follows. 1) Long-term thermal stability: length of 50m using the obtained pellets
A test piece of m, width 25 mm, and thickness 2 mm was prepared by the injection molding method. Test tube (inner diameter 34mm, outer diameter 45mm, length 350m
300 ml of a Nissan genuine long life coolant (trade name; hereinafter abbreviated as LLC) containing ethylene glycol as a main component and a test piece were put in m), and the test piece was immersed in the LLC. The test tube in which the test piece was immersed in LLC was subjected to LLC immersion treatment using a test tube aging tester adjusted to a temperature of 120 ° C. In addition, LLC is 5,000
The test tubes were replaced by time, and each test tube was charged with one type of test piece of each of the example and the comparative example. The long-term thermal stability was evaluated by an oven life test using a test piece which was subjected to LLC immersion treatment for a predetermined time shown in each table described later.
That is, the test piece was placed in a circulating hot air oven adjusted to a temperature of 150 ° C., and the time until the test piece was completely deteriorated (time until the tensile strength became 0) was measured (JIS K
(According to 7212), the long-term thermal stability was evaluated.
A material having excellent long-term thermal stability is a material having a large oven life value of a test piece subjected to LLC immersion treatment for 10,000 hours.

Examples 1 to 7 and Comparative Examples 1 to 12 MFR as polyolefin (load at 230 ° C. 2.16 k
Discharge amount of molten resin for 10 minutes when g is added) 6.0g / 10
To 100 parts by weight of an unstabilized powdery crystalline propylene homopolymer, 4,4'-having a molecular weight of 2,800 as compound A
Thio-bis (2-t-butyl-5-methylphenol) -formaldehyde condensate, distearyl disulfide as compound B, 2,4-bis (octylthio) -6- (4-hydroxy-
3,5-di-t-butylanilino) -1,3,5-triazine or
2,4-bis [(octylthio) methyl] -o-cresol and other additives were added to Henschel Mixer (trade name) in predetermined proportions shown in Table 1 below.
After stirring and mixing for 3 minutes, use a single-screw extruder with a diameter of 40 mm for 200
The mixture was melt-kneaded at 0 ° C. and pelletized. Comparative Example 1
As for 12 to 100 parts by weight of powdery crystalline propylene homopolymer having an MFR of 6.0 g / 10 min which is not stabilized, the respective prescribed amounts of the additives shown in Table 1 below are blended, and Melt-kneading was performed according to No. 7, and pellets were obtained. Using the obtained pellets, the long-term thermal stability was evaluated by the above test method. The results are shown in Table 1.

Examples 8-14, Comparative Examples 13-24 100 parts by weight of unstabilized powdery crystalline ethylene-propylene random copolymer (ethylene content 2.5% by weight) as MFR 7.0 g / 10 min as polyolefin 2,4'-thio-bis (2-methylphenol) -acetaldehyde condensate having a molecular weight of 1,390 as compound A, dilauryl disulfide as compound B, 2,4-bis (octylthio) -6-
(4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine or 2,4-bis [(octylthio) methyl]
-O-Cresol and other additives were added to the Henschel Mixer (trade name) in the proportions shown in Table 2 below, and the mixture was stirred and mixed for 3 minutes, then the caliber was 40 mm.
Was melt-kneaded at 200 ° C. with a single-screw extruder to produce pellets. Further, as Comparative Examples 13 to 24, 100 parts by weight of an unstabilized powdery crystalline ethylene-propylene random copolymer (ethylene content 2.5% by weight) having an MFR of 7.0 g / 10 min is shown in Table 2 below. A predetermined amount of each additive was blended and melt-kneaded according to Examples 8 to 14 to obtain pellets. Using the obtained pellets, the long-term thermal stability was evaluated by the above test method. The results are shown in Table 2.

Examples 15-21, Comparative Examples 25-36 100 parts by weight of unstabilized powdery crystalline ethylene-propylene block copolymer (ethylene content 8.5% by weight) as MFR 4.0 g / 10 min as polyolefin In addition, 4,4'-thio-bis (2-methyl-6-t-
Butylphenol) -propionaldehyde condensate, dimyristyl disulfide as compound B, 2,4-bis (octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine or Predetermined amounts of 2,4-bis [(octylthio) methyl] -o-cresol and other additives were placed in a Henschel mixer (trade name) at the blending ratios shown in Table 3 below, and mixed with stirring for 3 minutes. Then, the mixture was melt-kneaded at 200 ° C. with a single screw extruder having a diameter of 40 mm to form pellets. In addition, as Comparative Examples 25 to 36, MFR
4.0g / 10min unstabilized powdery crystalline ethylene
-Propylene block copolymer (ethylene content 8.5% by weight) was mixed with 100 parts by weight of each of predetermined amounts of the additives shown in Table 3 below, and melt-kneaded according to Examples 15 to 21. Pellets were obtained. Using the obtained pellets, the long-term thermal stability was evaluated by the above test method. The results are shown in Table 3.

Examples 22 to 28, Comparative Examples 37 to 48 MFR 8.0 g / 10 min as a polyolefin 70% by weight of unstabilized powdery crystalline propylene homopolymer, M
FR 7.0 g / 10 min unstabilized powdery crystalline ethylene-propylene-butene-1 terpolymer (ethylene content 2.5% by weight, butene-1 content 4.5% by weight) 5% by weight,
MI (amount of molten resin discharged at a load of 2.16 kg at 190 ° C for 10 minutes) 5.0 g / 10 minutes unstabilized powder Ziegler-Natta high density ethylene homopolymer
Unstabilized powdery amorphous ethylene-propylene random copolymer with 10% by weight and Mooney viscosity ML1 + 4 (100 ° C) of 25 (propylene content 25% by weight) 15% by weight in total 100 parts by weight In addition, compound A having a molecular weight of 3,750
4,4'-thio-bis (2-isoamyl-5-isopropylphenol) -butyraldehyde condensate, distearyl disulfide as compound B, 2,4-bis (octylthio) -6-
(4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine or 2,4-bis [(octylthio) methyl]
-O-Cresol and other additives were added to the Henschel mixer (trade name) in the prescribed proportions shown in Table 4 below, and the mixture was stirred and mixed for 3 minutes.
Was melt-kneaded at 200 ° C. with a single-screw extruder to produce pellets. Further, as Comparative Examples 37 to 48, powdery crystalline propylene homopolymer 70 having an unstabilized MFR of 8.0 g / 10 min.
Wt%, MFR 7.0 g / 10 min, powdered crystalline ethylene-propylene-butene-1 terpolymer not stabilized (ethylene content 2.5 wt%, butene-1 content 4.5 wt%) 5 Unstabilized powdered Ziegler-Natta high density ethylene homopolymer with wt% and MI of 5.0 g / 10 min
Unstabilized powdery amorphous ethylene-propylene random copolymer having a Mooney viscosity ML1 + 4 (100 ° C.) of 25 and 15% by weight, totaling 100% by weight Each part was blended with a predetermined amount of each of the additives shown in Table 4 below, and melt-kneaded according to Examples 22 to 28 to obtain pellets. Using the obtained pellets, the long-term thermal stability was evaluated by the above test method. The results are shown in Table 4.

The various additives shown in Tables 1 to 4 are as follows. Compound A [1]: 4,4'-thio-bis (2-t- with a molecular weight of 2,800
Butyl-5-methylphenol) -formaldehyde condensate Compound A [2]: molecular weight 1,390 4,4'-thio-bis (2-methylphenol) -acetaldehyde condensate Compound A [3]: molecular weight 2,300 4,4 '-Thio-bis (2-methyl-6-t-butylphenol) -propionaldehyde condensate Compound A [4]: 4,4'-thio-bis (2-isoamyl-5-isopropylphenol) -butyl having a molecular weight of 3,750 Aldehyde Condensate Compound B [1]: Dilauryl disulfide Compound B [2]: Dimyristyl disulfide Compound B [3]: Distearyl disulfide Compound B [4]: 2,4-bis (octylthio) -6- (4- Hydroxy-3,5-di-t-butyl anilino)
-1,3,5-Triazine Compound B [5]: 2,4-bis [(octylthio) methyl]
-o-cresol

Phenolic Antioxidant 1: 1,3,5-Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene Phenolic Antioxidant 2: Bis [3,3-bis (3'-t-butyl-4'-hydroxyphenyl
Le) Butyric acid] Ethylene glycol S
Terphenol Antioxidant 3: Bis [2- (3'-t-butyl-5 '
-Methyl-2'-hydroxybe
) -4-Methyl-6-t-butylphenyl] terephthalate
Rate Phenol-based antioxidant 4: 4,4'-thio-bis (2-t-butyl-5-methylphenol) -formaldehyde condensate with a molecular weight of 740 Phenol-based antioxidant 5: 4,4'- with a molecular weight of 5,500 Thio-
Bis (2-t-butyl-5-methylphenol) -formaldehyde condensate

Thioether Antioxidant 1: Dimyristyl Thiodipropionate Thioether Antioxidant 2: Pentaerythritol-
Tetrakis (3-laurylchi
Opropionate) Thioether antioxidant 3: bis [2-methyl-4- (3-
Lauryl thiopropionyl
(Oxy) -5-t-butylphenyl] sulfide thioether antioxidant 4: 3,9-bis (2-laurylthioethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane

Phosphorus antioxidant 1: bis (2,4-di-t-butylphenyl) -pentaerythritol-diphosphite Phosphorus antioxidant 2: bis (2,4,6-tri-t-butyl) Phenyl) pentaerythritol-diphosphite phosphorus antioxidant 3: tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylene-di-
Phosphonite Phosphorus antioxidant 4: 2,2'-ethylidene-bis (4,6-di-t
-Butylphenyl) Fluorophosphite Ca-St: Calcium stearate

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

The examples and comparative examples shown in Table 1 are the cases where a crystalline propylene homopolymer was used as the polyolefin. As can be seen from Table 1, Examples 1-7
Is a mixture of Compound A and Compound B according to the present invention, and Examples 1 to 7 and Comparative Example 1 (compound A alone is incorporated: the composition proposed in JP-A-53-16745). It is understood that in Examples 1 to 7, the long-term thermal stability is remarkably improved by the combined use of the compound B. Comparing Comparative Examples 2 to 5 and Examples 1 to 7 in which thioether antioxidants 1 to 4 were blended in place of the compound B in the compositions of Examples 1 to 3, the long term of Comparative Examples 2 to 5 was compared. Although the thermal stability is improved to the same level as or slightly higher than that of Comparative Example 1, it is still insufficient. Further, instead of the compound A, phenolic antioxidants 1 to 3
And compound B or thioether antioxidant 1,
Comparing Comparative Examples 6 to 10 and Examples 1 to 7 in which 3 was blended respectively, Comparative Examples 6 to 10 are excellent in oven life value at the initial stage of LLC immersion treatment, but in long-term thermal stability. Still not enough.

Further, in place of Compound A in the composition of Example 1, Comparative Example 11 in which phenolic antioxidants 4 to 5 having a molecular weight, which is one of the requirements for Compound A, is outside the range of the present invention, are added. -12 and Examples 1-7, the long-term thermal stability of Comparative Examples 11-12 is still insufficient. That is, although Comparative Example 11 is excellent in the oven life value in the initial stage of the LLC immersion treatment, a long-term LLC immersion treatment causes a significant decrease in long-term thermal stability, and Comparative Example 12 is a decrease phenomenon as in Comparative Example 11. Although not observed, it can be seen that the oven life value is small at any stage of the LLC immersion treatment. Therefore,
It is apparent that the comparative examples that do not simultaneously satisfy the combination of the two components of the compound A and the compound B according to the present invention do not exhibit the effects of the present invention. That is, it can be said that the long-term thermal stability obtained in the present invention is a unique effect that can be seen only when the compound A and the compound B are used in combination in the present invention.

Tables 2 to 4 show crystalline ethylene-propylene random copolymers, crystalline ethylene-propylene block copolymers or crystalline propylene homopolymers, and crystalline ethylene-propylene-butene- as polyolefins, respectively. 1 A mixture of a terpolymer, a Ziegler-Natta high density ethylene homopolymer and an amorphous ethylene-propylene random copolymer is used.
The effects similar to those described above were also confirmed for these.

[0032]

EFFECTS OF THE INVENTION The composition of the present invention is (1) superior to the conventionally known polyolefin composition with improved long-term thermal stability.
When formed into a molded product, the long-term thermal stability of the molded product is remarkably excellent. (2) Applications that require long-term thermal stability in various molding fields, that is, heat exchange systems (for example, radiator tanks, because of their extremely long-term thermal stability)
It can be suitably used for a reserve tank and a heater part).

Claims (1)

[Claims] 1. A 4,4′-thio-bisphenol-aliphatic aldehyde condensate having a molecular weight of 1,000 to 4,000, and one or more thioether compounds selected from the following, based on 100 parts by weight of a polyolefin. 0.05-5 respectively
A stabilized polyolefin composition containing 1 part by weight. Dialkyl disulfide 2,4-bis (octylthio) -6- (4-hydroxy-3,5-di
-t-Butylanilino) -1,3,5-triazine 2,4-bis [(octylthio) methyl] -o-cresol