JP2748508B2 - Stabilized polyethylene composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a stabilized polyethylene composition. More specifically, the present invention relates to a polyethylene composition having excellent heat-resistant processing stability and heat-resistant discoloration during high-temperature molding.

<Conventional technology> In general, polyethylene is molded by various methods such as extrusion molding, blow molding, and injection molding. However, cross-linking due to thermal degradation during molding processing lowers the fluidity (MI value) and causes gelation. And the polyethylene is discolored during repeated molding. In particular, in an extrusion molding method such as melt spinning, a gelled product of polyethylene is generated by continuous operation for a long time, and clogging of a screen pack of an extruder occurs due to the gelled product,
As a result, there is a problem that the productivity is remarkably reduced, for example, a discharge amount is reduced and frequent replacement of the screen pack is required. In addition, when formed into a film or a sheet, a fisheye gel is generated, which causes a problem that printability and the like are significantly reduced.

As a method for improving the processing stability and discoloration during the molding process, JP-A-62-223248 discloses a polyethylene-containing phenolic compound represented by the following general formula [I] (hereinafter referred to as compound A); A phenolic compound represented by the following general formula [II] (hereinafter referred to as compound B), a phosphite-based compound represented by the following general formula [III] (hereinafter referred to as compound C), and a phosphite represented by the following general formula [IV] It has been proposed to incorporate one or more compounds selected from among system compounds (hereinafter referred to as compound D).

(In the formula, R ₁ is defined as hydrogen or a methyl group, and R _{2 to} R ₉ are each defined as hydrogen or a same or different alkyl group having 1 to 8 carbon atoms.) Problem> Although the invention disclosed in this publication has a considerable improvement over the previous stabilization technology, it is still not sufficiently satisfactory. That is, 2-t-butyl-6- (3-t-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenyl which is most preferred in the publication.
Acrylate (Compound A) and 1,3,5-trimethyl-2,
4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (compound B), bis (2,4-di-t-
Butylphenyl) pentaerythritol diphosphite (Compound C) or tetrakis (2,4-di-t-butylphenyl) 4,4′-biphenylene diphosphonite (Compound D) There still remain problems such as insufficient heat-resistant processing stability during molding, and discoloration due to heat history due to repeated extrusion. Therefore, further improvements to these have been demanded.

<Means for Solving the Problems> The present inventors have conducted intensive studies in order to further improve these insufficient characteristics, and as a result, have reached the present invention.

That is, the present invention relates to a method for preparing (A) 2-t-amyl-6- [1- (3,5-di-t-
Amyl-2-hydroxyphenyl) ethyl] -4-t-
An object of the present invention is to provide a stabilized polyethylene composition comprising amylphenyl acrylate and (B) a phosphorus-based antioxidant. By such a composition, the heat-resistant processing stability at the time of high-temperature molding is improved, that is, the effect of suppressing the decrease in fluidity and the effect of preventing the formation of a gelled product are obtained, and the heat-resistant discoloration during repeated extrusion is also improved. .

2- (t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] -4 of the above (A)
T-amylphenyl acrylate is polyethylene 10
It is preferably used in the range of 0.01 to 1 part by weight based on 0 part by weight. If the compounding amount is less than 0.01 part by weight, the desired heat-resistant processing stability and heat-resistant discoloration are not sufficient, and if it exceeds 1 part by weight. May cause bleed.

The phosphorus-based antioxidant (B) is polyethylene 100
It is preferably used in the range of 0.01 to 1 part by weight with respect to parts by weight. If the compounding amount is less than 0.01 parts by weight, the desired heat-resistant processing stability and heat-resistant discoloration are not sufficient. Cause

The phosphorus-based antioxidant used in the present invention is not particularly limited. For example, distearyl pentaerythritol diphosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2 , 6-Di-t-butyl-4-methylphenyl)
Pentaerythritol diphosphite, tris (2,4-di-t-butylphenyl) phosphite, tris (nonylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) 4,4'-
Biphenylene diphosphonite, and the like. Among these, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, tris (2,4-di-t-butylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) ) 4,4'-
Biphenylene diphosphonite is preferred.

The polyethylene used in the present invention includes high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high-molecular-weight polyethylene, and the like.Specific examples include a homopolymer of ethylene, or ethylene and propylene. , Butene-1, pentene-1, hexene-1, octene-1, or α or more of these two or more
-Copolymers with olefins can be exemplified.

In the composition of the present invention, various additives usually added to polyethylene, for example, phenol-based, sulfur-based antioxidants, ultraviolet absorbers, hindered amine-based light stabilizers, metal deactivators (copper Harm-preventing agents), nucleating agents, lubricants, antistatic agents, anti-fogging agents, anti-blocking agents, drip-free agents, pigments, radical generators such as peroxides, dispersants or neutralizing agents such as metal soaps and An inorganic filler (for example, talc, mica, clay, glass fiber) or the like may be blended.

Specific examples of these additives that can be used in the present invention include the following.

Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, 4,4'-thiobis (3-methyl-6-t-butylphenol), and n-octadecyl 3- (3, 5-di-t-butyl-4-
Hydroxyphenyl) propionate, triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], 3,9-bis [1,1-dimethyl-2- {β- (3 -T-butyl-4-hydroxy-5-methylphenyl) propionyloxydiethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, tetrakis [methylene-3- (3,5-di) -T-butyl-4-hydroxyphenyl) propionate] methane, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, tris [2- {3- (3,5-di-t- Butyl-4-hydroxyphenyl) pyropionyloxydiethyl] isocyanurate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-
Butyl-4-hydroxybenzyl) benzene and the like. Especially, if the gas resistance discoloration (NO _x gas, fuel gas propane gas, resistance to discoloration caused by automobile exhaust gas) is required, 3,9-bis [1,1-dimethyl-2-{beta-( Preferred is a combination of 3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxydiethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane.

Examples of the sulfur-based antioxidants include dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, and pentaerythrityl tetrakis (β- Lauryl thiopropionate).

Examples of the ultraviolet absorber include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and bis (5-benzoyl-4-hydroxy-2-). Methoxyphenyl) methane, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- [2-hydroxy-3- (3,4,5, 6-tetrahydrophthalimidomethyl) -5-methylphenyl] benzotriazole, 2- (3-t-butyl-2-hydroxy-5-methylphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t -Butyl-2-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-5-t-octylphenyl)
Benzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzo Triazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2,2'-methylenebis [6-2H-benzotriazol-2-yl) -4- (1 , 1,3,3-tetramethylbutyl)
Phenol], poly (3-11) (ethylene glycol) and methyl 3-
[3- (2H-benzotriazol-2-yl) -5-t
-Butyl-4-hydroxyphenyl] propionate, 2-ethylhexyl 3- [3-t-butyl-5- (5
-Chloro-2H-benzotriazol-2-yl) -4-
Hydroxyphenyl] propionate, octyl 3- [3-t-butyl-5- (5-chloro-
2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate, methyl 3- [3-tert-butyl-5- (5-chloro-2H
-Benzotriazol-2-yl) -4-hydroxyphenyl] propionate, 3- [3-tert-butyl-5- (5-chloro-2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionic acid, 2,2'-methylenebis [4-t-butyl-6- (2H-
Benzotriazol-2-yl) phenol] and the like.

Examples of hindered amine light stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl succinate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6, Polycondensate with 6-tetramethylpiperidine, poly [(6-morpholino-1,3,5-triazine-2,4-
Diyl) {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], bis (1,2, 2,6,6-pentamethyl-4-piperidyl)
2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, 4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy]- 1- [2- ｛3-
(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxydiethyl] -2,2,6,6-tetramethylpiperidine, bis (1,2,2,6,6-pentamethyl-4- Piperidyl)
Decanedioate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, poly [｛6- (1,1,3,3-tetramethyl (Butyl) imino-1,3,5-triazine-2,4-diyl} (2,2,6,6-
Tetramethyl-4-piperidyl) imino {hexamethylene} (2,2,6,6-tetramethyl-4-piperidyl) imino}], 1,2,3,4-butanetetracarboxylic acid and 1,2,2 Mixed ester of 1,6,6-pentamethyl-4-piperidinol and 1-tridecanol, 1,2,3,4-butanetetracarboxylic acid and 2,2,6,6-tetramethyl-4-piperidinol and 1-tridecanol Mixed esterified product with tridecanol, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis (2-
Mixed esterified product with (hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane, 1,2,3,4-butanetetracarboxylic acid and 2,2, Mixed ester with 6,6-tetramethyl-4-piperidinol and 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane A polycondensate of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine and 1,2-dibromoethane, 2-methyl-2- (2,2 , 6,6-Tetomethyl-4-piperidylamino) -N- (2,2,6,6-tetramethyl-4-
Piperidyl) propionamide, N, N ', 4,7-tetrakis [4,6-bis {N-butyl-N
-(2,2,6,6-tetramethyl-4-piperidyl) amino {-1,3,5-triazin-2-yl] -4,7-diazadecane-1,10-diamine, N, N ', 4-tris [4,6-bis {N-butyl-N- (2,
2,6,6-tetramethyl-4-piperidyl) amino {-1,
(3,5-triazin-2-yl) -4,7-diazadecane-1,
10-diamine, bis (1-acryloyl-2,2,6,6-tetramethyl-
4-piperidyl) 2,2-bis (3,5-di-t-butyl-4)
-Hydroxybenzyl) malonate, N, N ', 4,7-tetrakis [4,6-bis {N-butyl-N
-(1,2,2,6,6-pentamethyl-4-piperidyl) amino}]-1,3,5-triazin-2-yl] -4,7-diazadecane-1,10-diamine, N, N ', 4-Tris [4,6-bis {N-butyl-N- (1,
2,2,6,6-pentamethyl-4-piperidyl) amino}-
(1,3,5-triazin-2-yl) -4,7-diazadecane-
1,10-diamine, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 1,2,2,6,6 -Pentamethyl-4-piperidyl methacrylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate and the like.

<Example> Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Examples 1 to 3 and Comparative Examples 1 to 6 A dry blend of a phenolic compound and a phosphorus compound described below with respect to 100 parts by weight of a high-density polyethylene (MI = 15, 190 ° C.) in the amounts shown in Table 1 After that, the mixture was melt-kneaded at 200 ° C. with a single-screw extruder having a diameter of 30 mm, and pelletized.
The following physical properties were measured using the obtained pellets, and the results are shown in Table 1.

Processing stability (melt stability): Using a melt indexer (manufactured by Takara Kogyo Co., Ltd.)
According to K-7210, the fluidity (MI value: g / 10 min) after residence at 300 ° C. for 5 minutes and 60 minutes was evaluated. The smaller the difference between the fluidity after staying for 5 minutes and the fluidity after staying for 60 minutes, the more excellent the high-temperature processing stability is.

Gelling (crosslinking) prevention: Using a 30 mm diameter T-die extruder, cylinder temperature 240
To 280 ° C., a die temperature of 280 ° C., the thickness in the resin pressure 200 kg / cm ² 0.4
A sheet having a thickness of 0.3 mm was detected and counted in 1000 cm ^{2 of} this sheet. The smaller the fisheye value is, the less the gelled substance is, and the more excellent the gelation preventing property is.

Discoloration prevention: Using a single-screw extruder having a diameter of 30 mm, extrusion was repeated five times at 300 ° C., and the obtained pellets were further molded into a 1 mm-thick flat plate with a 5.5 oz injection molding machine (250 ° C.). The difference between the YI value of the 1 mm thick flat plate for the first and fifth repetitions, that is, ΔY
I was evaluated for discoloration prevention. The smaller the value of ΔYI, the more excellent the discoloration preventing property is.

The symbols of the phenolic compound and the phosphorus compound described in Table 1 mean the following, respectively.

AO-1 2-t-amyl-6- [1- (3,5-di-t-
Amyl-2-hydroxyphenyl) ethyl] -4-t-
Amylphenyl acrylate AO-2 2-t-butyl-6- (3-t-butyl-5-
Methyl-2-hydroxybenzyl) -4-methylphenyl acrylate AO-3 1,3,5-Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene P- 1 bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite P-2 tetrakis (2,4-di-t-butylphenyl)
4,4'-biphenylenediphosphonite P-3 tris (2,4-di-t-butylphenyl) phosphite <Effect of the Invention> The polyethylene composition of the present invention is remarkably excellent in heat-resistant processing stability and heat-resistant discoloration during high-temperature processing and molding. As a result, in extrusion molding such as melt spinning that performs long-time continuous operation, problems such as a decrease in productivity due to gelation of polyethylene are significantly reduced, and particularly high heat-resistant processing stability is required. It can be used advantageously for fiber applications. It is also advantageous for applications such as films that are repeatedly used as recycled products.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kikumitsu Inoue 3-1-198, Kasuganaka, Konohana-ku, Osaka-shi Within Sumitomo Chemical Co., Ltd. (72) Inventor Tamaki Ishii Kasuga, Konohana-ku, Osaka-shi, Osaka Sumitomo Chemical Co., Ltd. (1) 98, Sumitomo Chemical Industries Co., Ltd. (72) Inventor Kanako Toda, 3-1-1, Kasuganaka, Konohana-ku, Osaka-shi, Osaka

Claims (3)

(57) [Claims] (1) 100 parts by weight of polyethylene: (A) 2-t-amyl-6- [1- (3,5-di-t-
Amyl-2-hydroxyphenyl) ethyl] -4-t-
A stabilized polyethylene composition comprising 0.01 to 1 part by weight of amylphenyl acrylate and (B) 0.01 to 1 part by weight of a phosphorus antioxidant. 2. The method according to claim 1, wherein the phosphorus-based antioxidant is bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, tris (2,4-di-t-butylphenyl) phosphite or tetrakis (2,4 -Di-t-butylphenyl) 4,4'-
The polyethylene composite according to claim 1, which is biphenylene diphosphonite. 3. The method according to claim 1, wherein the polyethylene is a homopolymer of ethylene or ethylene and propylene, butene-1, pentene-1,
3. The polyethylene composition according to claim 1, which is hexene-1, octene-1, or a copolymer thereof with two or more α-olefins.