JPH02225544A - Stabilized polyethylene composition - Google Patents

Abstract

PURPOSE:To obtain a polyethylene composition excellent in processing stability and discoloration resistance by adding a phenolic compound and a phosphite compound to a polyethylene. CONSTITUTION:A polyethylene composition prepared by adding 0.01-1 pts.wt. each of a phenolic compound of formula I and a phosphite compound of formula II to 100 pts.wt. polyethylene. In the formulas, R1 is H or a 1-3C alkyl; R2-R5 are each a 1-9C alkyl, a cyclohexyl or a 1-methylcyclohexyl; R6 is H or a methyl; R7 and R9 are each a 3-9C branched alkyl; R8 is H or a 1-9C alkyl. When the above amount of addition is below 0.01 pt.wt., the processing stability and discoloration resistance of the polyethylene composition cannot be fully exhibited, while when this amount is above 1 pt.wt., there is no effect of further improving the processing stability and discoloration resistance, which is uneconomical.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to stabilized polyethylene compositions. More specifically, the present invention relates to an ethylene composition that is excellent in preventing oxidative deterioration of polyethylene during melt cross-fertilization.

[Prior art] Generally, polyethylene is relatively cheap and has excellent mechanical properties, so it is used for injection molded products, blow molded products, films,
It is used to manufacture various molded products such as sheets and fibers. However, when polyethylene is molded at a temperature higher than the melting point of the polyethylene, it undergoes oxidative deterioration due to the heat generated during melt crosslinking, and crosslinking of the polyethylene reduces processability, that is, melt stability, and deteriorates the appearance of the molded product. In addition, problems such as color and odor (1) occur due to oxidative deterioration.Especially in extrusion molding methods such as melt spinning, crosslinking of polyethylene progresses due to continuous molding for a long period of time, resulting in the formation of gelled products. The gelled product causes clogging of the screen back, which causes problems such as a decrease in the discharge amount and a significant decrease in productivity due to the replacement of screen punctures.Furthermore, when formed into a film or sheet, Because of the problem of fish eyes caused by high molecular weight components caused by gelation reactions, conventional methods have been developed to prevent thermal oxidative deterioration during melt-kneading of polyethylene to improve melt stability and anti-gelation properties. Various phenolic and phosphorus antioxidants have been used alone or in combination for the purpose of improving this.

[Problems to be Solved by the Invention] However, a composition in which only conventional phenolic antioxidants, especially low molecular weight phenolic antioxidants such as 2,6-di-butyl-p-cresol, are blended with polyethylene. Although the product has excellent thermal oxidative deterioration resistance (hereinafter referred to as processing stability, and processing stability means melting stability and gelation prevention property) during melt mixing, the There is a drawback that the molded product has one color due to the antioxidant used. Furthermore, compositions made by blending only a high molecular weight phenolic antioxidant with polyethylene have drawbacks in processing stability and coloring properties caused by the high molecular weight phenolic antioxidant. *Ta.

Although the composition obtained by combining polyethylene with the above-mentioned low molecular weight phenolic antioxidant and high molecular weight phenolic antioxidant has excellent processing stability, almost no synergistic effect is observed due to the combination. On the other hand, there is a problem in that as the amount of the phenolic antioxidant increases, the resulting molded product becomes noticeably colored.

On the other hand, a composition made by blending only a phosphorus antioxidant with polyethylene significantly improves the coloring problem seen in molded articles obtained from a composition made by blending the aforementioned phenolic antioxidant. However, there is a drawback that the melt stability, which is processing stability, is significantly reduced when subjected to severe thermal history due to several times of melt-kneading. For this reason, it is conceivable to use a high molecular weight phenolic antioxidant that has a synergistic effect with the phosphorus antioxidant in combination.

However, with such combination systems, it is possible to some extent to improve processing stability, especially melt stability, and coloration caused by the antioxidant used, which are problems of the prior art, but it is still not sufficient. In the combination system of high molecular weight phenolic antioxidant and phosphorus antioxidant, although the gelation prevention effect of the combination system is recognized to some extent, it is still not sufficient. In extrusion molding, the 11t shape is strongly desired to improve gelation prevention among processing stability.

In order to solve the above-mentioned problems regarding the above-mentioned polyethylene composition, that is, the disadvantages of processing stability and coloring property, the present inventor previously disclosed a specific acrylate group-containing phenolic antioxidant in JP-A No. 62-223248. We proposed an ethylene composition using a specific phosphite compound or a phosphorus antioxidant made of a specific phosphite compound, but we were not satisfied with this and continued to investigate further.

As a result, a phenol-based compound represented by the following general formula [13] (hereinafter referred to as compound A) and a phosphite-based compound represented by the following general formula [1] (hereinafter referred to as compound A) were added to polyethylene.
It has been found that a composition containing a specific amount of each of the compounds (hereinafter referred to as compound B) can solve the drawbacks of the above-mentioned polyethylene composition, and based on this knowledge, the present invention has been completed.

R7 and Ro are branched alkyl groups having 3 to 9 carbon atoms,
(R8 represents hydrogen or an alkyl group having 1 to 9 carbon atoms, respectively.) The object of the present invention is to provide a polyethylene composition from which a molded article without coloring can be obtained.

[Means for solving problem l1] The present invention has the following configuration.

For 100 parts by weight of polyethylene, the following general formula [I]
A phenol-based compound represented by (hereinafter referred to as compound A) and a phosphite-based compound represented by the following general formula [■] (hereinafter referred to as compound B) were each 0.0
A stabilized polyethylene composition containing 1 to 1 part by weight.

(However, in the formula, R4 is hydrogen or an alkyl group having 1 to 3 carbon atoms, R2-R6 is an alkyl group having 1 to 9 carbon atoms, a cyclohexyl group, or 1-methylcyclohexyl group, and R8 is hydrogen or a methyl group, (However, R5 in 1 formula
represents hydrogen or an alkyl group having 1 to 3 carbon atoms, R2-R
5 is an alkyl group having 1 to 9 carbon atoms, a cyclohexyl group or a 1-methylcyclohexyl group, and R6 is hydrogen or a methyl group.

R7 and R6 are branched alkyl groups having 3 to 9 carbon atoms,
RS represents hydrogen or an alkyl group having 1 to 9 carbon atoms, respectively.) The polyethylene used in the present invention is a crystalline homopolymer of ethylene, an ethylene copolymer containing 50% by weight or more of ethylene component, and and propylene, butene
1. Crystalline, low crystalline or amorphous copolymers with IN or two or more α-olefins such as pentene-1,4-methyl-pentene-1, hexene-1, octene-1, non-crystalline Polyethylene such as ethylene-propylene-nonconjugated diene copolymer.

Copolymers of ethylene and vinyl acetate or acrylic esters, saponified products of the copolymers, copolymers of ethylene and unsaturated silane compounds, copolymers of ethylene and unsaturated carboxylic acids or their anhydrides, Examples include a reaction product of the copolymer and an irises ion compound, a modified polyethylene obtained by modifying the above-mentioned polyethylene with an unsaturated carboxylic acid or a derivative thereof, and a silane-modified polyethylene obtained by modifying the above-mentioned polyethylene with an unsaturated silane compound. However, it is logical to use these polyethylenes alone, 2.
It is also possible to use a mixture of more than one type of polyethylene.

In addition to the above-mentioned polyethylene, various synthetic rubbers (such as polybutadiene, polyisoprene, polychloroprene, and chlorinated polyethylene) are used.

Chlorinated polypropylene, fluororubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer ,
styrene-propylene-butylene-styrene block copolymers, etc.) or thermoplastic synthetic resins (e.g., polyolefins other than polyethylene such as polypropylene, polybutadiene 1 and pyry-4-methylpentene-1, polystyrene, styrene-acrylonitrile, etc.) Polymers, acrylonitrile-butadiene-styrene copolymers, polyamides, polyethylene terephthalates, polybutylene terephthalates, polycarbonates, polyvinyl chloride, fluororesins, etc.) can also be used in combination.

Crystalline ethylene homopolymer, 50% by weight ethylene component
A crystalline ethylene copolymer containing the above, including a crystalline ethylene-propylene copolymer, a crystalline ethylene-butene-1 copolymer, a crystalline ethylene-propylene-butene-1 ternary copolymer, and a crystalline ethylene copolymer. -Pentene-1 copolymer, crystalline ethylene-hexene-1 copolymer, and mixtures of two or more thereof are particularly preferably used.

Compound A used in the present invention is 2-t-butyl-
6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate, 2-t-
Butyl-6-(3-t-butyl-2-hydroxy-5-
ethylbenzyl)-4-ethyl phenyl acrylate, 2-nonyl-6-(3-nonyl-2-hydroxy-5
-methylbenzyl)-4-methylphenylacrylate, 2,4-di-nonyl-6-(3,5-di-nonyl-2
-hydroxybenzyl) phenyl acrylate, 2-cyclohexyl-6-(3-cyclohexyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate, 2-(1'-methylcyclohexyl).8-
[3-(1'-Methylcyclohexyl)-2-hydroxy-5-methylpenzyl-4-methylphenylacrylate, 2,4-di-methyl-6·[3,5-di-methyl-2-hydroxy( α-propylbenzyl)co phenyl acrylate, 2,4-di-butyl-6-(
3,5-di-butyl-2-hydroxybenzyl) phenyl acrylate, 2-t-butyl-8-[3-t-
Butyl-2-hydroxy-5-methyl (α-methylbenzyl)]-]4-methylphenylacryl, 2-
t-butyl-6-[3-t-butyl-2-hydroxy-
5-s-butyl (α-methylbenzyl)]-4.S-butylphenyl acrylate, 2,4-di-butyl-
6-[3,5-di-t-butyl-2-hydroxy (α-
methylbenzyl)] phenyl acrylate, 2-t-octyl-6-(3-t-octyl-2-hydroxy-5
-methylbenzyl)-4-methylphenylacrylate, 2-(1'-methylcyclohexyl)-6-[3-
(1'-methylcyclohexyl)-2-hydroxy-5
-Methyl(α-propylbenzyl)]-]4-methylphenylacrylate 2,4-di-methyl-6-(3,5
-di-methyl-2-hydroxybenzyl) phenyl acrylate, 2-t-butyl-6-(3-t-butyl-2
-hydroxy-5-methylbenzyl)-4-methylphenyl methacrylate, 2-t.butyl-8-(3-t-
Butyl-2-hydroxy-5-ethylbenzyl)-4-
Ethylphenyl methacrylate, 2-tunyl-8-(3
-nonyl-2-hydroxy-5-methylbenzyl)-4
-Methylphenyl methacrylate, 2,4-di-nonyl-6-(3,5-di-nonyl-2-hydroxybenzyl)phenyl methacrylate, 2-cyclohexyl-8-
(3-cyclohexyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl methacrylate, 2-(
1'-methylcyclohexyl) -8-[3-(1'-
methylcyclohexyl)-2-hydroxy-5-methylbenzylco-4-methylphenyl methacrylate, 2,
4-di-methyl-8-[3,5-di-methyl-2-hydroxy(α-propylbenzyl)cophenyl methacrylate, 2゜4-di-butyl-8-(3,5-di-butyl-2) -Hydroxybenzyl)phenyl methacrylate, 2-butyl-843-t-butyl-2-
Hydroxy-5-methyl (α-methylbenzyl)]
4-methylphenyl methacrylate 2-t-butyl-8
-[3-tert-butyl-2-hydroxy-5-3-butyl (α-methylbenzyl)] -4-s-butylphenyl methacrylate, 2.4-di-butyl-6-[3
, 5-di-butyl-2-hydroxy(α-methylbenzyl)]phenyl methacrylate, 2,7-octyl-6-(3-t-octyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl methacrylate, 2
- (1'-methylcyclohexyl) -6-[3-(
1'-methylcyclohexyl)-2-hydroxy-5-
Methyl(α-propylbenzyl)]-]4-methylphenylmethacrylate and 2,4-di-methyl-6-(3
, 5-di-methyl-2-hydroxybenzyl) phenyl methacrylate, in particular 2-t-butyl-
6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate, z-
t-butyl-6-[3-t-butyl-2- and droxy-
5-Methyl(α-methylbenzyl)]-]4-methylphenylacryl and 2,4-di-butyl-6-
[3,5-Di-1-butyl-2-hydroxy(α-methylbenzyl)]phenylacrylate is preferred. These compounds A can be used alone, but two or more compounds A can also be used in combination. The blending ratio of the compound A is 0.01 to 1 part by weight, preferably 0.05 to 0.5 part by weight, per 100 parts by weight of polyethylene. 0
．． If the amount is less than 1 part by weight, the effect of improving the processing stability and anti-coloring property of the polyethylene composition will not be sufficiently exhibited, and if it is more than 1 part by weight, it will not affect the processing stability and anti-coloring property. Not only is it impractical as no improvement effect can be expected, but it is also uneconomical.

Compound B used in the present invention includes bis(2゜6-di-i-propyl-4-methylphenyl)pentaerythritol-diphosphite, bis(2-i-propyl-4-methylphenyl),
6-Sheeptylphenyl)pentaerythritol-diphosphite, bis(2-i.propyl-4-methyl-
6-Sheeptylphenyl) pentaerythritol siphosphite, bis(2-i-propyl 4-ethyl-
6-butylphenyl) pentaerythritol diphosphite, bis(2-1-propyl-4,6-di-butylphenyl) pentaerythritol diphosphite, bis(2,6-ditobutyl-4-methylphenyl) pentaerythritol. Siphosphite, bis(2,6-di-i-butyl-4-ethylphenyl)pentaerythritol-diphosphite, bis(2,4
, 8-trimmed butylphenyl) pentaerythritol-diphosphite, bis(2,6-di-i-butyl-4-t-butylphenyl)pentaerythritol-diphosphite, bis(2,6-di-S-butyl-4-
methylphenyl) pentaerythritol-diphosphite.

Bis(2,6-di-S-butyl-4-ethylphenyl)
Pentaerythritol-diphosphite, bis(2,
4,6-tri-S-butylphenyl)pentaerythritol-diphosphite, bis(2,6-di-3-butyl-4-butylphenyl-osphite, bis(2-8-butyl-4-methyl-6
-t.butylphenyl)pentaerythritol-diphosphite, bis(2-s-butyl-4-ethyl-6-
t-butylphenyl) pentaerythritol-diphosphite, bis(2-s-butyl-4-i-butyl-6
-Sheeptylphenyl)pentaerythritol-diphosphite, bis(2,4-di-S-butyl-8-e.
butylphenyl) pentaerythritol-diphosphite, bis(2-s-butyl-4,6-di-butylphenyl)pentaerythritol-diphosphite,
Bis(2.6-di-butyl-butylphenyl)pentaerythritol-diphosphite, bis(2.6-di-butyl-4-methylphenyl)pentaerythritol-diphosphite.

Bis(2.6-di-butyl-4-ethylphenyl)pentaerythritol-diphosphite Bis(2
．． 8.dibutyl-4-n-propylphenyl)pentaerythritol-diphosphite, bis(2.8
-dibutyl-44-propylphenyl)pentaerythritol-diphosphite, bis(2,8-dibutyl-4-n-butylphenyl)pentaerythritol-diphosphite, bis(2,6-dibutyl-4.l - butylphenyl) pentaerythritol-diphosphite, bis(2,6-di-butyl-US-butylphenyl) pentaerythritol-diphosphite.

Bis(2,4.8-di-butyl-butyl)pentaerythritol-diphosphite, Bis(2,6-di-butyl-4-n-amylphenyl)pentaerythritol-diphosphite, Bis(2,6-di-butyl-4-n-amylphenyl) 1-butyl-4-i-amylphenyl)pentaerythritol-diphosphite, bis(2.6-di-butyl-4-5-amylphenyl)pentaerythritol-
Diphosphite, bis(2,6-di-t-butyl-4
-t-amylphenyl)pentaerythritol-diphosphite, bis(2,6-di-L-butyl-4-n-
hexylphenyl) pentaerythritol-diphosphite, bis(2,6-di-butyl-fun-heptyl)pentaerythritol-diphosphite, bis(2,6-di-butyl-4-n-octylphenyl)pentaerythritol-diphosphite, bis(2-di-butyl-4-n-octylphenyl)
, 6-di-butyl-4-cyoctylphenyl)pentaerythritol-diphosphite, bis(2-71-butyl-4-methyl-6-toamylphenyllite, bis(2-tert-butyl-4-methyl-6-s-
amyl phenyl) pentaerythritol-diphosphite, bis(2-t-butyl-4-methyl-a-t-amylphenyl) pentaerythritol-diphosphite, bis(2-mobutyl-4-methyl-6-t-octylphenyl) penta Erythritol-diphosphite, bis(2-t-butyl-4-ethyl-6-1-amylphenyl)pentaerythritol-diphosphite, bis(2-t-butyl-4-ethyl-6-s-11ruphenyl)pentaerythritol. Siphous Fight,
Bis(2-butyl-4.ethyl-8-t-amylphenyl)pentaerythritol-diphosphite, bis(2-t-butyl-4.ethyl-6-t.octylphenyl)pentaerythritol-diphosphite, bis( Examples include 2,4-di-1-butyl 8-t-amylphenyl) pentaerythritol diphosphite and bis(2,4-di-t-butyl-6-cyoctylphenyl) pentaerythritol diphosphite. (2,6-di-t-butyl-4-methylphenyl)pentaerythritol-diphosphite and bis(2,6-di-L-butyl-4-!I-butylphenyl)pentaerythritol-diphosphite are preferred, these compounds B The use of a single monkey is a mochi theory,
Two or more types of compounds B can also be used in combination. The blending ratio of compound B is 0 to 100 parts by weight of polyethylene.
．． 01 to 1 part by weight, preferably 0.05 to 0.5 part by weight. If the amount is less than 0.01 part by weight, the effect of improving the processing stability and anti-coloring property of the polyethylene composition will not be sufficiently exhibited, and if it is more than 1 part by weight, it will not affect the processing stability and coloring. Not only is it impractical as no improvement in preventive properties can be expected, but it is also uneconomical.

In the composition of the present invention, 1. various additives that are usually added to polyethylene, such as phenol type.

Antioxidants such as 1,000-onythyl-based and phosphorus-based antioxidants, light-determining agents,
Heavy metal deactivator (copper damage inhibitor), clarifying agent, nucleating agent,
Lubricants, antistatic agents, antifogging agents, antiblocking agents, non-dripping agents, flame retardants, flame retardant aids, pigments, radical generators such as peroxides, dispersants or neutralizers such as metal soaps, inorganic Fillers (e.g. talc, mica, clay, wollastonite).

Zeolite, asbestos, calcium carbonate, aluminum hydroxide, magnesium hydroxide, silicon dioxide, titanium dioxide, zinc oxide, magnesium oxide, zinc sulfide, barium sulfate, calcium silicate, aluminum silicate,
(glass fibers, potassium titanate, carbon fibers, carbon black, graphite, metal fibers, etc.) or coupling agents (such as silanes, titanates, borons, aluminates, zircoalkynates, etc.) The above-mentioned inorganic filler surface-treated with a treatment agent or organic filler (eg, hydrated, pulp, waste paper, synthetic fiber, natural fiber, etc.) can be used in combination without impairing the purpose of the present invention.

The composition of the present invention is prepared by adding predetermined amounts of Compound A and Compound B and the various additives mentioned above that are normally added to polyethylene to polyethylene using a conventional mixing device such as Hensel Mixer (trade name)% Super Mixer, ribbon blender, etc.
Mix using a Pan Bali mixer, etc., and use a normal single-screw extruder, twin-screw extruder, Brabender or roll, etc. to a melt mixing temperature of 120°C to 300°C, preferably 180°C to
It can be obtained by melt-kneading and pelletizing at 270°C.

The obtained composition is used to produce a desired molded article by various molding methods such as injection molding, extrusion molding, and blow molding.

[Effect] In the present invention, compound A and compound B are used in combination.

The mechanism of action itself is not clear as to how it works when a polyethylene composition is melt-mixed. However, the phenol antioxidant represented by Compound A is In a similar system), a presumed mechanism has been reported in which a radical is added to the double bond of the acrylate group to the compound, and the proton of the phenol's hydroxyl group moves to the generated active carbon radical, stabilizing it as a phenoxy radical. ing. *In addition, it is generally known that a phosphorus-based antioxidant consisting of a phosphite-based compound represented by Compound B acts as a peroxide decomposer.In the present invention, the above-mentioned Compound A and Compound B may be used together. As a result, a surprising synergistic effect that cannot be predicted from the combination with various conventionally known antioxidants is exhibited.

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The evaluation method used in Examples and Comparative Examples was as follows.

1) Processing stability (A > Melt stability) Measure the melt index (MI) of the obtained pellet (according to JIS K6780), and measure this as the first MI
shall be. Then, the obtained pellets were again melt-cross-wired at a melt-crosswire temperature of 270° C. to pelletize, and this process was repeated four times. Dissolve M and I of the obtained pellet.
Each time the kneading is carried out, measurements are taken again using the method described above, and these are measured in the second M1. I[3ML 4th M1. It will be the 5th MI.

Melt stability is defined by the following formula: M! Evaluation was made based on the retention rate.

(The 5th MI indicates the MI after passing through the extruder 5 times,
) If the MI retention value is close to 1.0, it indicates that the melt stability, which is the processing stability during repeated extrusion or molding processing, is excellent.

(B) Anti-gelation properties The anti-gelation properties were evaluated by any of the following methods using the obtained pellets.

(a) Using a T-die extruder with a fisheye diameter of 30 mm, the cylinder temperature is 1
90℃~250℃, die temperature 250℃, resin pressure 250℃
A sheet with a thickness of 0.4 m was prepared at kg/as 2G, and fins with a diameter of 0.3 m or more were detected and counted in this sheet 100001'. The smaller the fisheye value, the less the formation of high molecular weight components (gelled products), which indicates that the gelling prevention property is excellent.

(b) Extrusion characteristics (clogging of screen pack) diameter 2
Using a 0mm spinning machine (using a die with 50 nozzle holes with a diameter of 0.5mm and three 300mash screen packs), the cylinder temperature was 190°C to 250°C, the die temperature was 250°C, and the resin pressure was 30kg/ Start melt spinning at ax 2G, resin pressure is 50kg/am2
Continuous operation is performed until the resin pressure reaches 50kg/G.
The time (number of days) when cs 2G is reached is considered as clogging of the screen pack.

The larger the number of days, the less gelled products are formed and the better the gelling prevention properties are.

2) Y I (Yellowness) of the resulting beret.
Index) (based on JIS K7103)
Then, let the YI value at this time be i[IY I. Then, the obtained pellets were melt-kneaded again at a melt-kneading temperature of 1270° C. to pelletize, and this process was repeated four times. The YI of the obtained pellet was measured again by the above method each time the melting crosstalk was carried out, and these were measured as @2YI and 3rd Y1, respectively.
．． 4th Y1. I! It will be 5YI.

The coloring prevention property was evaluated based on the magnitude of ΔYI defined by the following formula.

ΔYI = 5th Yr - 1st YI (5th YI indicates YI after passing through the extruder 5 times,
) The smaller the value of ΔY1, the better the coloring prevention property.

Examples 1-6. Comparative Examples 1 to 15 MI as polyethylene (load 2.1 at 190°C
Discharge amount of molten resin for 10 minutes when adding 6 kg)2
．． 0g / 10 min.
83 g/cs3) 100 parts by weight of Compound A: 2-L-butyl-〇-(3-t-butyl-2-bitroxy-5-methylbenzyl) to 4-methylphenylacrylate, 2-t-butyl-6 -[3-t-butyl-2-
Hydroxy-5-methyl (α・methylbenzyl')]
-]4-methylphenylacrylate or 2,4-di-butyl-6-[3,5-di-butyl-2-hydroxy(α-methylbenzyl)]phenylacrylate, as compound B bis(2, Butyl 4-
methylphenyl) pentaerythritol-siphosphite or bis(2,6-di-t-butyl-4-s-
Butylphenyl) pentaerythritol-diphosphite and other additives were added in predetermined amounts to Il1 as described below.
The mixture was added to Hensel Ikuxa (trade name) at the mixing ratio shown in the table, stirred and mixed for 3 minutes, and then melted and mixed at 200 DEG C. in a single-screw extruder with a diameter of 40 mm to form pellets. *
Comparative Examples 1 to 15 were unstabilized powdered Ziegler-Natsuta high-density ethylene homopolymer (density 0.963 g/am3) with Ml of 2-Ot/10 min.
Predetermined amounts of the additives listed in Table 111 below were added to 0 parts by weight, and the mixture was melt-kneaded in accordance with Examples 1 to 6 to obtain pellets.

Using the obtained pellets, processing stability was evaluated for melt stability, anti-gelling properties (fish eyes), and anti-coloring properties using the test method described above. These results are shown in Table 1.

Examples 7 to 1 Comparative Examples 16 to 30 M r as polyethylene 3. Og/10 min unstabilized powdered Ziegler-Natsuta high density ethylene-butene-1 copolymer (density 0.948 g/am
3. Unstabilized powdery low density ethylene homopolymer (density 0.918 (/c■
3) 10% by weight and Mooney viscosity MLI+4 (100
°C) 65 unstabilized powdered non-grade ethylene-
2-t-butyl-6-(3-e-butyl-2
-Hydroxy・5-methylbenzyl)-4-methylphenylacrylate, 2-t-butyl-6-[3-t-butyl-2-hydroxy-5-methyl(α-methylbenzyl') ]-]4-methyl Phenyl acrylate or 2,4-di-butyl-6-[3,5-di-L-butyl-2-hydroxy (α-methylbenzyl)] phenyl acrylate, as compound B bis(2,6-di-butyl-6-[3,5-di-L-butyl-2-hydroxy (α-methylbenzyl)] Monobutyl-4-methylphenyl)pentaerythritol-
Hensel Mixer (trade name) was prepared by mixing the prescribed amounts of diphosphite or bis(2,6-di-butyl-1-s-phthylphenyl)pentaerythritol-diphosphite and other additives in the proportions listed in Table 2 below. After stirring and mixing for 3 minutes,
The mixture was melt-kneaded at 200°C using a single-screw extruder to form pellets. In addition, as Comparative Examples 16 to 30, Ml was set to 3.0/
Unstabilized powdered Ziegler-Natsuta high density ethylene-butene-1 copolymer (density 0.9
Unstabilized powdered low-density ethylene homopolymer with an MI of 0.5.710 minutes and a density of 0.48 g/c, 0.014 ethyl branches/1000 carbons).
918 g/cm3) and 10% by weight of an unstabilized powdery amorphous ethylene-propylene random copolymer (propylene content 25% by weight) with a Mooney viscosity M L 1+4 (100 °C) of 65 A total of 100 parts by weight was blended with predetermined amounts of each of the additives listed in Table 112 below, and melt-kneaded according to Examples 7 to 12 to obtain pellets.

The obtained pellets were used to evaluate processing stability, such as melt stability, anti-gelling properties (fish eyes), and anti-coloring properties, according to the test methods described above. These results are shown in Table 2.

Examples 13 to 18, Comparative Examples 31 to 45 Unstabilized powdered Ziegler-Natsuta high-density ethylene-propylene copolymer (density 0.950 (/c
*', 2-t-butyl-6-(3-t
-butyl-2-hydroxy-5-methylbenzyl)-4
-Methylphenyl acrylate, 2-t-butyl-6-
[3-t-Butyl-2-hydroxy-5-methyl (α-
methylbenzyl)-4-methylphenylacrylate or 2,4-di-butyl-6-[3,5-di-
Savetyl-2-hydroxy (α-methylbenzyl)]
Phenyl acrylate, compound B as bis(2,8-
The respective prescribed amounts of di-butyl-4-methylphenyl)pentaerythritol-diphosphite or bis(2,6-di-butyl-4-s-butylphenyl)pentaerythritol-diphosphite and other additives are shown in Table 3 below. The mixture was put into a Hensel mixer (trade name) at the mixing ratio described in , and after stirring and blending for 3 minutes, it was melted and mixed at 200° C. using a single-screw extruder with a diameter of 40 m to form pellets. *MI is 2 as Comparative Examples 31 to 45.
Unstabilized powdered Ziegler-Natsuta high density ethylene-propylene copolymer (density 0.950/c, 3° methyl branched 3-08/1
A predetermined amount of each of the additives listed in Table 113 below was added to 100 parts by weight of 000 carbon).

A beret was obtained by melt mixing according to Examples 13 to 18.

Using the obtained pellets, the processing stability was determined by the above test method, including melt stability and anti-gelling properties (extrusion properties).
The clogging of the screen pack)) and coloring prevention properties were evaluated. These results are shown in the fJ3 table.

The compounds and additives related to the present invention shown in Tables 1 to 3 are as follows.

Compound A [f]: 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate Compound A [n]: 2-t-butyl-6- [3-t
-Butyl-2-hydroxy-5-methyl (α-methylbenzyl)-4-methylphenylacrylate compound A [III]: 2,4-di-butyl-
6-[3,5-di-monobutyl-2-hydroxy (α-
Methylbenzyl) cobenyl acrylate compound B [11: Bis(2,8-di-butyl-4-methylphenyl)pentaerythritol-di-phosbuite compound B [111: Bis(2,8-di-butyl-4-methylphenyl) s-butylphenyl) pentaerythritol-diphosphite phenolic antioxidant 1: 2,8-di-butyl-P-cresol phenolic antioxidant M2: tetrakis[methylene-3
-(3',5'-di-savetyl-4'.hydroxyphenyl)propionate] Methane phosphorus antioxidant 1: Tris(2,4-di-t-butylphenyl)phosphite phosphorus antioxidant 2: Tetrakis (2,4-di-butylphenyl) -4,4'-biphenylene di-phosphite Phosphorus antioxidant 3: Bis(2,4-di-butylphenyl)-pentaerythritol-siphosphite Ca
-5t: Calcium stearate WE11! In the Examples and Comparative Examples described in Section t, a Ziegler-Natsuta high-density ethylene homopolymer was used as the polyethylene. As can be seen from Table 1, Examples 1 to 6 are mixtures of Compound A and Compound B related to the present invention, and Examples 1 to 6 and Comparative Examples 1 to 7 (Compound A related to the present invention, When compared with Compound B or other phenolic antioxidants or phosphorus antioxidants (individually blended), Examples 1 to 6 are excellent in both processing stability and coloring prevention properties. I understand that.

In particular, in Examples 1 to 6, there was almost no decrease in melt stability even after five heat cycles, as is clear from the MI retention rate, which indicates melt stability, which is a processing property in repeated extrusion at high temperatures. , it can also be seen that the value of fish eyes caused by the gelation reaction is also small. Comparing Comparative Examples 8 to 12 and Examples 1 to 6, which are combination systems of phenolic antioxidant 2 and various phosphorus antioxidants including phenolic antioxidant 1 or compound B, which are conventionally known, In Comparative Examples 8 to 12, although the processing stability was improved to some extent by the combination, it was still not sufficient, and the effect on 11a prevention was still not sufficient. Comparative Example 1 using various phosphorous antioxidants other than Compound B
Comparing Examples 3 to 15 and Examples j to 6, Comparative Examples 13 to 1
Although the processing stability and anti-coloring properties of Example 5 are improved compared to Comparative Example 1 in which Compound A was mixed alone, they are still not sufficient. Therefore, a remarkable synergistic effect was observed by using Compound B in combination with Compound A. I know that it will happen.

Table 2 shows polyethylenes using a mixture of Ziegler-Natsuta high-density ethylene-butene-1 copolymer, low-density ethylene homopolymer, and amorphous ethylene-propylene random copolymer. The same effect as mentioned above was also confirmed.

Furthermore, Table 113 shows a case in which a Ziegler-Natsuta high-density ethylene-propylene copolymer was used as the polyethylene, and the same effects as described above were confirmed for this as well. In particular, as is clear from the results of clogging of the screen pack, it can be seen that the composition of the present invention exhibits a remarkable anti-gelation effect.

〔Effect of the invention〕

I of the present invention! Compared to polyethylene compositions that use conventionally known phenolic antioxidants and phosphorus antioxidants alone or in combination, Kaimono has (1) significantly superior processing stability and discoloration resistance during molding; ing.

(2) Since it has extremely excellent melt stability, which is processing stability when subjected to heat history due to several melt cross-wires, it can be advantageously used in applications where it is used as recycled products (films, sheets, etc.).

(3) Long series II! In extrusion molding operations such as melt spinning operations, problems such as decreased productivity due to gelation of polyethylene are significantly reduced.

that's all

Claims (4)

[Claims] (1) A phenolic compound represented by the following general formula [I] (hereinafter referred to as compound A) and a phosphorite-based compound represented by the following general formula [II] (hereinafter referred to as compound B) are added to 100 parts by weight of polyethylene. A stabilized polyethylene composition comprising 0.01 to 1 part by weight of each of the following. ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[II] (However, in the formula, R_1 is hydrogen or an alkyl group having 1 to 3 carbon atoms, and R_2 to R_5 are carbon atoms. R_6 is hydrogen or a methyl group, R_7 and R_9 are branched alkyl groups having 3 to 9 carbon atoms, R_8
each represents hydrogen or an alkyl group having 1 to 9 carbon atoms. ) (2) R_2, R_5 in general formulas [I] to [II]
, R_7 and R_9 are t-butyl groups (1)
The stabilized polyethylene composition described in ). (3) Compound A is 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate, 2-t-butyl-6-[3
-t-butyl-2-hydroxy-5-methyl(α-methylbenzyl)]-4-methylphenylacrylate, 2
, 4-di-t-butyl-6-[3,5-di-t-butyl-2-hydroxy(α-methylbenzyl)]phenylacrylate or a mixture of two or more thereof. stabilized polyethylene composition. (4) Compound B is bis(2,6-di-t-butyl-4
-Methylphenyl)pentaerythritol-diphosphite, bis(2,6-di-t-butyl-4-s-butylphenyl)pentaerythritol-diphosphite, or a mixture of two or more thereof. Claim (1)
The stabilized polyethylene composition described.