JPH0334496B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyolefin resin compositions having excellent thermal and oxidative stability. Polyolefin resin has excellent physical, chemical,
Because it has electrical properties, it can be processed into molded products, pipes, sheets, films, etc. by various methods such as blow molding, extrusion molding, injection molding, or calendar processing, and is used in many fields. When polyolefin resins such as polyethylene and polypropylene are used alone, they will deteriorate due to the effects of heat and oxygen during processing or use, and their physical properties will deteriorate significantly with phenomena such as softening, embrittlement, and discoloration. well known. In order to prevent such a phenomenon, various phenol-based, phosphorus-based, sulfur-based, and other antioxidants have been added singly or in combination during the production and processing steps of polyolefin resins. For example, 2,6-di-t-butyl-4-methylphenol, n-octadecyl-β-(3,5-
di-t-butyl-4-hydroxyphenyl)propionate, tetrakis[methylene-3-(3,
5-di-t-butyl-4-hydroxyphenyl)
-propionate] methane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, 1,
1,3-tris(2-methyl-4-hydroxy-
Using antioxidants such as 5-t-butylphenyl)butane or combining these antioxidants with dilaurylthiodipropionate, diristylthiopropionate, distearylthiopropionate or pentaerythritol-tetrakis(β -dodecylthiopropionate) and other methods are known. However, these methods are still not fully satisfactory in terms of thermal and oxidative stability. As a result of various studies to solve these problems, the present inventors have found that by blending a specific phenol compound and a specific sulfur compound into a polyolefin resin, the present inventors can overcome the conventional combination technology of antioxidants. It has now been discovered that a very unexpected and surprising synergistic effect can be obtained, and moreover, surprisingly, it has been found that it has extremely superior thermal and oxidative stability compared to the prior art, leading to the present invention. That is, the present invention provides tetrakis[methylene-
3-(3-methyl-5-t-butyl-4-hydroxyphenyl)propionate]methane [compound] and general formula (In the formula, R represents an alkyl group having 4 to 20 carbon atoms) Pentaerythritol-tetrakis (β-alkylthiopropionate) [Compound]
The object of the present invention is to provide a stabilized polyolefin resin composition containing the following in a ratio of 1:0.5 to 15 (weight ratio). Tetrakis [methylene-3 used in the present invention]
-(3-Methyl-5-t-butyl-4-hydroxyphenyl)propionate] methane is a combination of pentaerythritol and 3-(3-methyl-5-t-butyl-4-hydroxyphenyl)propionic acid,
Alternatively, it can be produced by a conventional esterification reaction with an acid halide, acid anhydride or mixed acid anhydride thereof, or by a conventional transesterification reaction with a lower alkyl ester thereof. In addition, as a phenolic compound similar to tetrakis[methylene-3-(3-methyl-5-butyl-4-hydroxyphenyl)propionate]methane used in the present invention, Japanese Patent Publication No. 42-9651 discloses 3 and 5 -Dialkyl-4-hydroxyphenyl group skeleton compounds are described, but in such phenolic compounds, the two alkyl groups at the o-position of the hydroxyl group are t-butyl groups, that is, sterically hindered dialkyl-substituted phenols. It is based on the concept of a derivative, and a specific compound is tetrakis[methylene-3-(3,5-di-t-butyl-4-
Hydroxyphenyl)propionate]methane is described. However, the compound () used in the present invention is a dialkyl-substituted phenol derivative in which one of the two alkyl groups at the o-position of the hydroxyl group is a methyl group without steric hindrance. It is distinguished from the group of dialkyl-substituted phenol derivatives described in the literature. In pentaerythritol-tetrakis (β-alkylthiopropionate) represented by the above general formula, which is another component used in the present invention, the substituent R represents an alkyl group having 4 to 20 carbon atoms, but it is stable under heat and oxidation. From the viewpoint of properties, an alkyl group having 6 to 18 carbon atoms is preferred, and an alkyl group having 12 carbon atoms is particularly preferred. Examples of such compounds include pentaerythritol-tetrakis (β-hexylthiopropionate), pentaerythritol-tetrakis (β-dodecylthiopropionate), and pentaerythritol-tetrakis (β-octadecylthiopropionate). . In the polyolefin resin composition of the present invention, the total amount of compound () and compound () added is usually 0.01 to 5 parts by weight, preferably 0.05 to 1 part by weight, based on 100 parts by weight of the polyolefin resin. The combined weight ratio of compound () to compound () is 0.5 to 15, preferably 1 to 10, more preferably 2 to 6 per 1 of compound (). Here compound () is for compound ()
If the amount of the compound () is less than 0.5 times by weight, it is difficult to obtain the desired effect, and even if the amount of the compound () exceeds 15 times by weight, it is difficult to obtain a commensurate effect, which is economically disadvantageous. In the present invention, in order to blend the compound () and the compound () into the polyolefin resin, the known equipment and operation method for mixing and blending stabilizers, pigments, fillers, etc. into the polyolefin resin can be applied almost as is. The polyolefin resin composition of the present invention may contain other additives, such as ultraviolet absorbers, light stabilizers, antioxidants, metal deactivators, metal soaps, nucleating agents,
It may also contain lubricants, antistatic agents, flame retardants, pigments, fillers, and the like. In particular, ultraviolet absorbers, hindered amine light stabilizers, etc., such as 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-
Octoxybenzophenone, 2(2'-hydroxy-5'-methylphenyl)benzotriazole, 2
(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2(2
-Hydroxy-3',5'-di-t-butylphenyl)-5-chloro-benzotriazole, 2(2'-
Hydroxy-3',5'-di-amyl phenyl)benzotriazole, [2,2'-thiobis(4-t-
octyl phenolate)]-butylamine Ni salt,
2,2,6,6-tetramethyl-4-piperidinylbenzoate, bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, 2-
(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butyl-malonate bis(1,2,
2,6,6-pentamethyl-4-piperidyl),
1-[2-{3-(3,5-di-t-butyl-4-
hydroxyphenyl)propionyloxy}ethyl]-4-[3-(3,5-di-t-butyl-4-
hydroxyphenyl)propionyloxy]-2,
By adding 2,6,6-tetramethylpiperidine, dimethyl succinate/1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, etc. Light resistance can be improved. Further, by adding another phosphite-based antioxidant to the composition of the present invention, the hue can be improved. Examples of these phosphite-based antioxidants include distearylpentaerythritol diphosphite, tris(2,
4-di-t-butylphenyl) phosphite, tris(2-t-butyl-4-methylphenyl) phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di- t-butylphenyl)-
Examples include 4,4'biphenylene diphosphite. The polyolefin resins stabilized by the present invention include low density polyethylene, medium-high density polyethylene, linear low density polyethylene, polypropylene, polyα-olefins such as polybutene-1, propylene-ethylene random or block copolymers, ethylene- Poly-α-olefin copolymers such as butene-1-random copolymers, copolymers of poly-α-olefins and vinyl monomers such as maleic anhydride-modified polypropylene, and mixtures thereof are used, but among these, particularly Effective against polypropylene. EXAMPLES Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto. Example 1 After mixing the following formulation in a mixer for 5 minutes,
The compound obtained by melting and kneading with a mixing roll at 180°C was formed into a sheet with a thickness of 1 mm using a hot press at 210°C, and a test piece of 40 x 40 x 1 mm was prepared. 30 of the specimen area in a gear oven at 160℃
% was measured, and this time was taken as the thermal embrittlement induction period, and the thermal and oxidation stability was evaluated. The results are shown in Table-1. <Formulation> Unstabilized polypropylene resin 100 parts by weight Calcium stearate 0.1 Test compound Variable In Table 1, the symbols for test compounds indicate the following compounds. I Tetrakis [methylene-3-(3-methyl-5-t-butyl-4-hydroxyphenyl)propionate] methane-1 Pentaerythritol-tetrakis (β-hexylthiopropionate) -2 Pentaerythritol-tetrakis (β-hexylthiopropionate) -dodecylthiopropionate) -3 Pentaerythritol-tetrakis (β-octadecylthiopropionate) AO-1 n-octadecyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate AO -2 Tetrakis [methylene-3-(3,5
-di-t-butyl-4-hydroxyphenyl)propionate]methane AO-3 1,3,5-trimethyl-2,4,6
-Tris(3,5-di-t-butyl-
4-hydroxybenzyl)benzene AO-4 1,1,3-tris(2-methyl-4
-hydroxy-5-t-butylphenyl)butane AO-5 dilaurylthiodipropionate AO-6 distearylthiodipropionate

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Claims (1)

[Scope of Claims] 1 Tetrakis [methylene-3-(3-methyl-
5-t-butyl-4-hydroxyphenyl)propionate] methane and general formula (In the formula, R represents an alkyl group having 4 to 20 carbon atoms) Pentaerythritol-tetrakis (β-alkylthiopropionate) represented by 1:0.5 to
15 (weight ratio). 2. The stabilized polyolefin resin composition according to claim 1, wherein the polyolefin resin is polypropylene. 3. Stabilization according to any one of claims 1 and 2, wherein the pentaerythritol-tetrakis (β-alkylthiopropionate) is pentaerythritol-tetrakis (β-dodecylthiopropionate). Polyolefin resin composition.